Certificate HTTPS could not create SSL relationship trust vb.net - vb.net

Question

I am consistently getting this error:
Could not establish trust relationship for the SSL/TLS secure channel
with authority 'dev1sintiaweb01'.
I am sure, I had signed the certificate. Why do I still get this error? What can I do to fix it?
This is my Server WebConfig.
<?xml version="1.0" encoding="UTF-8"?>
<configuration>
<configSections>
<sectionGroup name="applicationSettings" type="System.Configuration.ApplicationSettingsGroup, System, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089">
<section name="SpasiWebService.My.MySettings" type="System.Configuration.ClientSettingsSection, System, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" requirePermission="false" />
</sectionGroup>
</configSections>
<appSettings />
<system.web>
<compilation debug="true" strict="false" explicit="true" targetFramework="4.6.1">
</compilation>
<httpRuntime />
<pages controlRenderingCompatibilityVersion="4.0" />
</system.web>
<system.serviceModel>
<services>
<service name="SpasiService.IService1">
<endpoint address="basic" binding="basicHttpsBinding" contract="SpasiService.IService1" />
</service>
</services>
<bindings>
<basicHttpsBinding>
<binding maxBufferPoolSize="2147483647" maxBufferSize="2147483647" maxReceivedMessageSize="2147483647" transferMode="Streamed" >
<readerQuotas maxDepth="2147483647" maxStringContentLength="2147483647" maxArrayLength="2147483647" maxBytesPerRead="2147483647" maxNameTableCharCount="2147483647" />
</binding>
</basicHttpsBinding>
</bindings>
<behaviors>
<serviceBehaviors>
<behavior>
<serviceMetadata httpGetEnabled="true" httpsGetEnabled="true"/>
<serviceDebug includeExceptionDetailInFaults="false"/>
</behavior>
</serviceBehaviors>
</behaviors>
<protocolMapping>
<add binding="basicHttpsBinding" scheme="https" />
</protocolMapping>
<serviceHostingEnvironment aspNetCompatibilityEnabled="true" multipleSiteBindingsEnabled="true" />
</system.serviceModel>
<system.webServer>
<modules runAllManagedModulesForAllRequests="true" />
<directoryBrowse enabled="true" />
</system.webServer>
</configuration>
This is My Client AppConfig.
<?xml version="1.0" encoding="utf-8"?>
<configuration>
<configSections>
<sectionGroup name="userSettings" type="System.Configuration.UserSettingsGroup, System, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089">
<section name="DosirAsli.My.MySettings"
type="System.Configuration.ClientSettingsSection, System, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089"
allowExeDefinition="MachineToLocalUser" requirePermission="false"/>
</sectionGroup>
<!-- For more information on Entity Framework configuration, visit http://go.microsoft.com/fwlink/?LinkID=237468 -->
<section name="entityFramework"
type="System.Data.Entity.Internal.ConfigFile.EntityFrameworkSection, EntityFramework, Version=6.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089"
requirePermission="false"/>
</configSections>
<startup>
<supportedRuntime version="v4.0" sku=".NETFramework,Version=v4.6"/>
</startup>
<userSettings>
<DosirAsli.My.MySettings>
<setting name="strLinkMyBCA" serializeAs="String">
<value>https://mybcaportal/sites/ai/Aplikasi Pengawasan Internal/</value>
</setting>
</DosirAsli.My.MySettings>
</userSettings>
<entityFramework>
<providers>
<provider invariantName="System.Data.SqlClient" type="System.Data.Entity.SqlServer.SqlProviderServices, EntityFramework.SqlServer"/>
<provider invariantName="System.Data.SQLite.EF6" type="System.Data.SQLite.EF6.SQLiteProviderServices, System.Data.SQLite.EF6"/>
</providers>
</entityFramework>
<system.net>
<settings>
<servicePointManager checkCertificateName="false" checkCertificateRevocationList="false" />
</settings>
</system.net>
<system.serviceModel>
<bindings>
<basicHttpsBinding>
<binding name="BasicHttpsBinding_IService1" maxBufferPoolSize="2147483647" maxBufferSize="2147483647" maxReceivedMessageSize="2147483647" >
<readerQuotas maxDepth="2147483647" maxStringContentLength="2147483647" maxArrayLength="2147483647" maxBytesPerRead="2147483647" maxNameTableCharCount="2147483647" />
<security mode="Transport">
<transport clientCredentialType="Ntlm" />
</security>
</binding>
</basicHttpsBinding>
</bindings>
<!--<client>
</client>-->
<client>
<endpoint address="https://dev1sintiaweb01/WebServiceSpasi/Service1.svc"
binding="basicHttpsBinding" bindingConfiguration="BasicHttpsBinding_IService1"
contract="SpasiWebService.IService1" name="BasicHttpsBinding_IService" />
</client>
</system.serviceModel>
</configuration>
Error Stack Trace
Server stack trace: at
System.ServiceModel.Channels.HttpChannelUtilities.ProcessGetResponseWebException(WebException
webException, HttpWebRequest request, HttpAbortReason abortReason)
at
System.ServiceModel.Channels.HttpChannelFactory`1.HttpRequestChannel.HttpChannelRequest.WaitForReply(TimeSpan
timeout) at
System.ServiceModel.Channels.RequestChannel.Request(Message message,
TimeSpan timeout) at
System.ServiceModel.Dispatcher.RequestChannelBinder.Request(Message
message, TimeSpan timeout) at
System.ServiceModel.Channels.ServiceChannel.Call(String action,
Boolean oneway, ProxyOperationRuntime operation, Object[] ins,
Object[] outs, TimeSpan timeout) at
System.ServiceModel.Channels.ServiceChannelProxy.InvokeService(IMethodCallMessage
methodCall, ProxyOperationRuntime operation) at
System.ServiceModel.Channels.ServiceChannelProxy.Invoke(IMessage
message)
Exception rethrown at [0]: at
System.Runtime.Remoting.Proxies.RealProxy.HandleReturnMessage(IMessage
reqMsg, IMessage retMsg) at
System.Runtime.Remoting.Proxies.RealProxy.PrivateInvoke(MessageData&
msgData, Int32 type) at
DosirAsli.SpasiWebService.IService1.CekDomainTersedia(String
strDomain) at
DosirAsli.SpasiWebService.Service1Client.CekDomainTersedia(String
strDomain) in E:\Project CAAT\Web
PI\Web_PI\WebPI-DevBranch\DosirAsli\Connected
Services\SpasiWebService\Reference.vb:line 96 at
DosirAsli.Login.btnLogin_Click(Object sender, EventArgs e) in
E:\Project CAAT\Web PI\Web_PI\WebPI-DevBranch\DosirAsli\Login.vb:line
43