Thank you for considering Aspose. We are looking in to this issue. Can you please forward us your sample application? This will help us finding the issue.
Well, if you are building a web application, please use the Aspose.Cells.dll in the net2.0 directory.
The dll in net3.5_ClientProfile directory is used only for the console application with Net frame client profile. It is possible that you are using this dll? For complete reference, please check the readme.txt in the bin directory.