Diagnose SQL running from Power Shell - sql-server-2012

Question

I am trying to run a SQL from Power Shell(which is on my windows 7 64 bit desktop) and the remote database host is MS SQL Server 2012.
The code is:
$Server= ".\DB_HOST_NAME"
$Database = "master"
$UserSqlQuery= $("select count(*) from [master].[sys].[some_table]")
# executes a query and populates the $datatable with the data
function ExecuteSqlQuery ($Server, $Database, $SQLQuery) {
$Datatable = New-Object System.Data.DataTable
$Connection = New-Object System.Data.SQLClient.SQLConnection
$Connection.ConnectionString = "server='$Server';database='$Database';trusted_connection=true;"
$Connection.Open()
$Command = New-Object System.Data.SQLClient.SQLCommand
$Command.Connection = $Connection
$Command.CommandText = $SQLQuery
$Reader = $Command.ExecuteReader()
$Datatable.Load($Reader)
$Connection.Close()
$Datatable
return $Datatable
}
# declaration not necessary, but good practice
$resultsDataTable = New-Object System.Data.DataTable
$resultsDataTable = ExecuteSqlQuery $Server $Database $UserSqlQuery
Write-Host "Statistic: " $resultsDataTable
Write-Host "Message: Transaction Delay is " $resultsDataTable.Rows.Count
When I run this from Windows PowerShell, I get following errors:
Exception calling "Open" with "0" argument(s): "A network-related or
instance-specific error occurred while establishing a connection to
SQL Server. The server was not found or was not accessible. Verify
that the instance name is correct and that SQL Server is configured to
allow remote connections. (provider: SQL Network Interfaces, error: 26
- Error Locating Server/Instance Specified)" At H:\test2.ps1:11 char:5
+ $Connection.Open()
+ ~~~~~~~~~~~~~~~~~~
+ CategoryInfo : NotSpecified: (:) [], MethodInvocationException
+ FullyQualifiedErrorId : SqlException
Exception calling "ExecuteReader" with "0" argument(s): "ExecuteReader
requires an open and available Connection. The connection's current
state is closed." At H:\test2.ps1:15 char:5
+ $Reader = $Command.ExecuteReader()
+ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+ CategoryInfo : NotSpecified: (:) [], MethodInvocationException
+ FullyQualifiedErrorId : InvalidOperationException
Exception calling "Load" with "1" argument(s): "Value cannot be null.
Parameter name: dataReader" At H:\test2.ps1:16 char:5
+ $Datatable.Load($Reader)
+ ~~~~~~~~~~~~~~~~~~~~~~~~
+ CategoryInfo : NotSpecified: (:) [], MethodInvocationException
+ FullyQualifiedErrorId : ArgumentNullException
So the first error is at $Connection.Open() but I don't know anything about power shell to figure out what is wrong. I have tried running the same SQL on the same DB host and it does return a number.
Can I get some help to know what am I doing wrong here?

Answer 1

This code:
$Server= ".\DB_HOST_NAME"
should be:
$Server= "DB_HOST_NAME"
The specification ".\DB_HOST_NAME" is interpreted as a named instance (DB_HOST_NAME) running on your local box.