Hello All, Created a website in which I used Microsoft.Office.Interop.Excel using Visual Studio 2008 professional. I ran in on Windows XP 32-bit with Office 2007. Now I got a Windows 7 64bit with Office 2010 installed. I have several webpages that basically export values into Excel. When I do a publish from my Workstation to my Windows 2003 web server with Excel 2003 installed on it I get the following error message: Could not load file or assembly 'Microsoft.Office.Interop.Excel, Version=22.214.171.124, Culture=neutral, PublicKeyToken=71e9bce111e9429c' or one of its dependencies. The located assembly's manifest definition does not match the assembly reference. (Exception from HRESULT: 0x80131040) Any ideas? Now here is what I did. I picked from my GAC references version 11. of office. (I have 2 versions that I get to pick 11 and 12 but neither of them works for me and gives me the error.) I tried editing my web.config file by adding this code to it with no luck: Code: <add assembly="Microsoft.Office.Interop.Excel, Version=126.96.36.199, Culture=neutral, PublicKeyToken=71E9BCE111E9429C"/> <add assembly="office, Version=188.8.131.52, Culture=neutral, PublicKeyToken=71E9BCE111E9429C"/> <add assembly="Microsoft.Vbe.Interop, Version=184.108.40.206, Culture=neutral, PublicKeyToken=71E9BCE111E9429C"/> <add assembly="stdole, Version=7.0.3300.0, Culture=neutral, PublicKeyToken=B03F5F7F11D50A3A"/> Thanks for the help!