Permissions Issue With Http Driven Report In Web Iframe

Hi there,

I need to understand why I am getting the following error when I run my deployed (remote) report embedded in an iframe within a page of my web application.

error:
An
error has occurred during report processing. (rsProcessingAborted)
Query
execution failed for data set 'cnMOOR'. (rsErrorExecutingCommand)For
more information about this error navigate to the report server on the local
server machine, or enable remote error

This happens when I fire the following code from a commandbutton:
AppSettingsReader cfgApp = new AppSettingsReader();

string prefix = Convert.ToString(cfgApp.GetValue("reporturlprefix", typeof(System.String)));

string reporturl = prefix + "Client&rs:Command=Render&rs:Format=HTML4.0&rc:Parameters=False&supplierid=" + Session["supplierId"].ToString() + "&clientid=" + ddlClient.SelectedItem.Value + "&startdate=" + txtStartDate.Text + "&enddate=" + txtEndDate.Text + "&ownertype=1";

SpecificClient.Attributes.Add("src", reporturl);

SpecificClient is the ID of the Iframe

on the same page I created a link - which runs the report perfectly - no permission problems.
<a href="http://server2003msrs/reportserver?/moorreports/Client&rs:Command=Render&rs:Format=HTML4.0&rc:Parameters=False&supplierid=28&clientid=71&startdate=2007-01-01&enddate=2007-02-16&ownertype=1">Test</a>


I don't understand why these two controls are behaving differently.

I'd appreciate some guidance with this as the deadline looms...

Helen