Javascrip And asp.Net vb help needed

This method adds a javascript method to marks text box onkeydown, that javascript method takes the rowindex as argument. This code is being converted from C#. The method works fine using C#, but I got a “Conversion from string "javascript: DoPostBackWithRowInd" to type 'Double' is not valid “message when using the VB code below. Please help!


<script type="text/javascript" language="javascript">

        function DoPostBackWithRowIndex(rowIndex) {

            if (document.getElementById('<%=HdnSelectedRowIndex.ClientID%>') != null) {

                document.getElementById('<%=HdnSelectedRowIndex.ClientID%>').value = rowIndex;

            }

            return true;

        }

    </script>

 

'Event to handle the Users Grid DataBound Event
'This method adds a javascript method to marks text box onkeydown, that javascript method takes the rowindex as argument.

    Protected Sub GvUsersRowDataBound(ByVal sender As Object, ByVal eventArgs As GridViewRowEventArgs)

        If (eventArgs.Row.RowType = DataControlRowType.DataRow) Then

            Dim TxtMarks As TextBox = CType(eventArgs.Row.FindControl("TxtMarks"), TextBox)

            TxtMarks.Attributes.Add("onkeydown", "javascript:return DoPostBackWithRowIndex('" + eventArgs.Row.RowIndex + "');")

        End If

 

    End Sub