Error viewing reports


I have installed Tackle on a web server that already had SQL Reporting Services 2005 (SP3) installed. Reports in reporting services are displayed fine. Tackle works fine for all the database grid pages, but when trying to view any of the reports I initially received a dotnet error stating it could not find the ReportingServices.Common.WebForms.dll assembly. I noticed that this file was not in the Bin directory of Tackle, I copied it in this folder from my Reporting Services installation and now i get past this error but receive an error stating it failed because:
Failed to load expression host assembly. Details: Could not load file or assembly 'expressionhost19e2b216e83d4bad90e785e010eec493, Version=10.7.50727.42, Culture=neutral, PublicKeyToken=null' or one of its dependencies. Failed to grant permission to execute. (Exception from HRESULT: 0x80131418)
any ideas??