Trying to get the status of mirrored databases using powershell - sql-server

Question

I am trying to test the following script in powershell which gets the status of the mirrored databases.
#SQL Variables
$sqlservers = "APNSQL01"
#SQL database mirroring status
$body +=echo "------------Originating Server-----------"`r`n""`r`n""
Import-Module "sqlps" -DisableNameChecking
$body +=echo "--------Status of mirrored databases---------"`r`n""`r`n""
foreach ($server in $sqlservers){
$body +=echo "Database mirroring state on $server
"
$body += Invoke-Sqlcmd -Query "USE master
SELECT sys.database_mirroring.mirroring_state_desc
,sys.databases.name
FROM sys.database_mirroring INNER JOIN sys.databases ON sys.database_mirroring.database_id=sys.databases.database_id
WHERE mirroring_state_desc IS NOT NULL" -ServerInstance "$server" | out-string
}
When I run this code, I get the following error :
Invoke-Sqlcmd : 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: Named Pipes Provider, error: 40 - Could not open a connection to
SQL Server)
At C:\Users\ctxadmin\Desktop\SQL.ps1:20 char:11
+ $body += Invoke-Sqlcmd -Query "USE master
+ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+ CategoryInfo : InvalidOperation: (:) [Invoke-Sqlcmd], SqlException
+ FullyQualifiedErrorId : SqlExectionError,Microsoft.SqlServer.Management.PowerShell.GetScriptCommand
Invoke-Sqlcmd :
At C:\Users\ctxadmin\Desktop\SQL.ps1:20 char:11
+ $body += Invoke-Sqlcmd -Query "USE master
+ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+ CategoryInfo : ParserError: (:) [Invoke-Sqlcmd], ParserException
+ FullyQualifiedErrorId : ExecutionFailureException,Microsoft.SqlServer.Management.PowerShell.GetScriptCommand
My SQL server is a STANDARD database. It has no mirror. Is that the issue?
What might the error be?