Error: Must Declare the Scalar Variable

Here's my code:

Public Function selectReturnsByUserId( limit As Integer, userid As String ) As DataSet 



    Dim sql As String = " SELECT TOP " & limit & " pr.ProductId, p.Title, p.Barcode, pr.ScanDate, pr.UserId, pr.ReturnStatus" & _
                        " FROM " & tablename & " pr " 开发者_Go百科& _
                        "   INNER JOIN " & StaticValues.TABLENAME_PRODUCT & " p ON pr.ProductId = p.ProductId" & _
                        " WHERE pr.UserId = @UserId"

    Dim cmd As SqlClient.SqlCommand = New SqlClient.SqlCommand( sql )

    cmd.Parameters.AddWithValue( "@UserId", userid ) 

    Return _select( cmd )

End Function

Which Calls:

Protected Function _select(ByVal cmd As SqlClient.SqlCommand) As DataSet

    Dim ds As New DataSet
    Dim myAdapter As New System.Data.SqlClient.SqlDataAdapter(cmd.CommandText, DBConnection.getInstance().getConnection().ConnectionString)
    myAdapter.Fill( ds, tablename )

    Return ds

End Function

And when I try to run it, I get this error:

Must declare the scalar variable "@UserId"

On this line:

myAdapter.Fill( ds, tablename )

How can I fix that line?

Thanks

You never passed the parameter to the SqlDataAdapter.

You should change the _select method to use the original SqlCommand, or to copy its parameters.