One thing you can dp is check if the following lines return the actual value you need to do a Connect-Viserver
$vCenterIP = Get-MOLDatabaseData -connectionString $SQLConnectionString -isSQLServer -query "SELECT vCenterIP FROM server_table"
$vCenterUser = Get-MOLDatabaseData -connectionString $SQLConnectionString -isSQLServer -query "SELECT UserID FROM server_table"
$vCenterPassword = Get-MOLDatabaseData -connectionString $SQLConnectionString -isSQLServer -query "SELECT Password FROM server_table"
Maybe do a write-host to see the variable contents in each line right after and before doing a Connet-Viserver?
