How to add WCF maxClockSkew - wcf

Question

I have added the maxClockScrew to my WCF service config file because it gives me an error when I try to call it over the internet but when I changed the my client time zone to server time zone it works fine(when both in UTC +10.00 it works that means no time difference) or if I set both time to be sync from internet then it works fine.
This is my service config file,
<?xml version="1.0"?>
<configuration>
<appSettings>
<add key="Data Source" value="WIN-HDG2"/>
<add key="Initial Catalog" value="DEV"/>
<add key="User ID" value="sa"/>
<add key="Password" value="ssa"/>
<add key="Major version" value="1"/>
<add key="Minor Build" value="1"/>
</appSettings>
<connectionStrings/>
<system.web>
<compilation debug="true" targetFramework="4.0">
</compilation>
<authentication mode="Windows"/>
<pages controlRenderingCompatibilityVersion="3.5" clientIDMode="AutoID"/>
</system.web>
<system.serviceModel>
<services>
<service behaviorConfiguration="ABService.ServiceBehavior"
name="ABService.Service">
<endpoint address="" binding="wsHttpBinding" name="ValidatorEndpoint" bindingConfiguration="ABService.ServiceBehavior"
contract="ABService.IService">
<identity>
<dns value="localhost" />
</identity >
</endpoint>
<endpoint address="mex" binding="mexHttpBinding" contract="IMetadataExchange" />
<host>
<baseAddresses>
<add baseAddress="http://localhost/" />
</baseAddresses>
</host>
</service>
</services>
<behaviors>
<serviceBehaviors>
<behavior name="ABService.ServiceBehavior">
<serviceMetadata httpGetEnabled="true"/>
<serviceDebug includeExceptionDetailInFaults="true" />
<serviceCredentials>
<serviceCertificate findValue="AB548"
storeLocation="LocalMachine"
storeName="My"
x509FindType="FindBySubjectName" />
<userNameAuthentication userNamePasswordValidationMode="Custom"
customUserNamePasswordValidatorType="ABService.Validator.UserNamePassValidator,ABService" />
</serviceCredentials>
</behavior>
</serviceBehaviors>
</behaviors>
<bindings>
<wsHttpBinding>
<binding name="ABService.ServiceBehavior" >
<readerQuotas maxDepth="320" maxStringContentLength="8192000" maxArrayLength="16384000" maxBytesPerRead="999930473" maxNameTableCharCount="16384000"/>
<security mode="Message">
<message clientCredentialType="UserName"/>
</security>
</binding>
</wsHttpBinding>
<customBinding>
<binding name="ABService.ServiceBehavior">
<textMessageEncoding />
<security authenticationMode="Kerberos">
<localClientSettings maxClockSkew="00:07:00" />
<localServiceSettings maxClockSkew="00:07:00" />
<secureConversationBootstrap>
<localClientSettings maxClockSkew="00:30:00" />
<localServiceSettings maxClockSkew="00:30:00" />
</secureConversationBootstrap>
</security>
<httpTransport />
</binding>
</customBinding>
</bindings>
please some one help me with this issue....