tns could not resolve when using vbs script with oracle connector

Error:

D:\PRTG Network Monitor\custom sensors\EXE\oraclevb3.vbs(14, 1) OraOLEDB: ORA-12154: TNS:could not resolve the connect identifier specified

Script:

Dim strSQL
Dim strUsername
Dim strPassword
Dim snpData
Dim dbMyDBConnection

Set snpData = CreateObject("ADODB.Recordset")
Set dbMyDBConnection = CreateObject("ADODB.Connection")
strUsername = "user"
strPassword = "pass"

dbMyDBConnection.ConnectionString = "Provider=OraOLEDB.Oracle;Data Source=MyDB;User ID=" & strUsername & ";Password=" & strPassword & ";"
dbMyDBConnection.Open

strSQL = "select count(*) from requests"

snpData.Open strSQL, dbMyDBConnection

While Not snpData.EOF
    WSCript.Echo snpData.Fields(0).Value & ":ok"
    snpData.MoveNext
Wend

snpData.Close
dbMyDBConnection.Close

Set snpData = Nothing
Set dbMyDBConnection = Nothing

Others:
1. The server has oracle client installed with tnsnames configured to MyDB.
2. Running the script on command line works ok.
EDIT by Paessler: Adjusted formatting.