A first chance exception of type 'System.Data.SqlClient.SqlException' occurred in System.Data.dll

I'm trying to pull data from database using a stored procedure to return to an autocomplete extender. It all worked fine with one stored procedure but not with the second one, which has exactly the same SQL code behind it...
Ok here is the code from my web service:
    Public Function getAutocompleteTitles(ByVal prefixText As String, ByVal count As Integer) As String()

        Dim titelAdapter As moviesetsTableAdapters.SelectMoviesetsByTitleTableAdapter = New moviesetsTableAdapters.SelectMoviesetsByTitleTableAdapter
        Dim titels As DataTable = titelAdapter.GetMoviesetsBytitleUnique(prefixText)
        'Dim titels As DataTable = titelAdapter.GetMoviesetsBytitle(prefixText)
        Dim items As New List(Of String)

        For Eac ...