When I run the following script line locally on an SQL Server machine, it executes perfectly:

Backup-SqlDatabase -ServerInstance $serverName -Database $sqldbname -BackupFile "$($backupFolder)$($dbname)_db_$($addinionToName).bak"

$serverName contains a short name of the SQL Server instance. SQL Server is 2012, so these new cmdlets work like a charm.

On the other hand, when I am trying to perform a DB backup from a TeamCity agent machine like this (Through Invoke-Command cmdlet):

function BackupDB([String] $serverName, [String] $sqldbname, [String] $backupFolder, [String] $addinionToName)
{
    Import-Module SQLPS -DisableNameChecking

    Backup-SqlDatabase -ServerInstance $serverName -Database $sqldbname -BackupFile "$($backupFolder)$($dbname)_db_$($addinionToName).bak"
}

Invoke-Command -computername $SQLComputerName -Credential $credentials -ScriptBlock ${function:BackupDB} -ArgumentList $SQLInstanceName, $DatabaseName, $BackupDirectory, $BakId

results in an error:

Failed to connect to server $serverName. + CategoryInfo : NotSpecified: (:) [Backup-SqlDatabase], ConnectionFailureException + FullyQualifiedErrorId : Microsoft.SqlServer.Management.Common.ConnectionFailureException,Microsoft.SqlServer.M anagement.PowerShell.BackupSqlDatabaseCommand

What is the correct way to execute Backup-SqlDatabase cmdlet remotely?