vb.net Code works locally but not on web server - mysql

Question

I've an interesting problem. One of my database related code works good on local machine. But it doesn't return anything from when published on the third party web server.
Following is the code snippet :
Public Function getUserAuthDataWithUserId(ByRef Connection As MySqlConnection,
ByVal UserId As String
) As DataTable
Dim cmd As String
cmd = "select * from tbl_md_userauth where tf_userid = '" + UserId + "' "
getUserAuthDataWithUserId = ExecuteSQL(Connection, cmd)
End Function
And the ExecuteSQL function is :
Public Function ExecuteSQL(ByRef Connection As MySqlConnection,
ByVal SQLStatement As String
) As DataTable
Dim ds As New DataSet
Dim da As New MySqlDataAdapter
Try
da = New MySqlDataAdapter(SQLStatement, Connection)
da.Fill(ds, "tbl_Return")
ExecuteSQL = ds.Tables("tbl_Return")
Catch ex As Exception
msgbox ("exception !")
End Try
End Function
Be assured that :
The database table has correct data. And the code works correctly when connecting from local machine to remote desktop.
The code works correctly when using local IIS and local database.
I've also tried republishing the code twice or thrice.
Helpdesk of web server says there is no problem with their server.
Any clue on what is wrong ?

Answer 1

It appears that you are swallowing your exceptions. The code appears to use a msgbox to display the error, but that will appear on the server under a hidden profile and not be sent to the browser for display. You need some other way of displaying or logging the error that works in a web environment.
That being said, are you able to get any connections to the database and just this method is failing, or are all of your database requests failing? I suspect that you are using integrated authentication in your database configuration, but the same user doesn't work on the server because IIS is running as a different user in the app pool. Try changing your development environment to point to your database on the server and see if you get any errors that way. If you are using a hosting environment, I recommend setting up a named user in your database and using that in your connection string rather than using integrated authentication.

Answer 2

Ultimately, it found to be a server side problem. The Helpdesk fixed it. I am yet to know what precisely they have fixed. I'll problably post it over here as soon as I hear from them.
Thanks to all of you guys who've contributed.