Analytics Software

I have successfully integrated with OBIEE's Web Services to pull back HTML for specific reports. I am now moving on to filtering the reports using the ReportParams structure. I have found virtually no documentation on how to do this. I would essentially like to pass through a parameter inside of the htmlViewService object in order to filter a report. I have something like this:

ReportParams reportParams = new ReportParams();
reportParams.filterExpressions[0] = "3050"; // have even tried: reportParams.filterExpressions[0] = "Project ID equals 3050"
obiconn.m_HTMLservice.addReportToPage(pageID, reportName, reportRef, null, reportParams, null, sessionID);

I am getting an error: Object reference not set to an instance of an object (it is happening specifically on the reportParams.filterExpression[0] = "3050"

I'm assuming that I am not using the filter expression array properly. Can someone please help?

Thanks.