Reporting Services Table Grouping

I am using Table grouping in one of my reports and the report is used in a webapplication coded using Vb .net framework 1.1.
I need some assistance with Microsoft SQL Reporting Services. I am using a VB.NET 1.1. Report viewer is used. In my report i have implemented Grouping which displays EXpand/Collapse image(+/-). The report is hosted in another server. The report is working Properly when i take a preview or view the report directly from the report server. But when i view the report through the web application the Expand/collapse image is not displayed.
code used:
<td valign="top" height="100%">
<cc1:ReportViewer id="rvrUnitSnapshot" runat="server" height="100%" Width="100%" style="Z-INDEX: 101; LEFT: 168px; POSITION: absolute; TOP: 512px"
BorderStyle="None" Parameters="True" Toolbar="True"></cc1:ReportViewer>
</td>
I am explicitly setting the following in my VB code.
Protected WithEvents rvrUnitSnapshot As Microsoft.Samples.ReportingServices.ReportViewer
rvrUnitSnapshot.Toolbar = Microsoft.Samples.ReportingServices.ReportViewer.multiState.True
rvrUnitSnapshot.Parameters = Microsoft.Samples.ReportingServices.ReportViewer.multiState.False

Thanks