Hi, I receive this error "No default member found for type 'Guid'." when I run my application.

db = New SqlConnection(GetConnectionString())

Dim strSQL As String
strSQL = "SELECT GUID FROM MyLog WHERE MyID = '" & strID & "'"

strGUIDTracker = GetSingleData(strSQL)


Function GetSingleData(ByVal sqlText As String) As String
        Dim sd As String
        Dim oConn As SqlConnection
        oConn = New SqlConnection(GetConnectionString())
        Dim strSQLCmd As SqlCommand = New SqlCommand(sqlText, oConn)
        [B]sd = strSQLCmd.ExecuteScalar(System.Data.CommandBehavior.CloseConnection)[/B]
        Return sd
    End Function

The highlighted line is the statement where the error occured at. I've tested my SQL statements, it really contains a single record.

Can someone please kindly explain to me why am I getting this error here? Thanks alot.