Report View - Could not load file or assembly

I use VS2008 to develop a web application.

When I open a local report, it's report datasource does not show. I click the report->DataSource to see it's d开发者_如何学Catasource, but it appear an error message:

Could not load file or assembly ###

But the file or assembly does exist.

How can I solve this problem?

I searched everywhere and didnt found a solution for this.

Thanks.

Copy the assembly to the folder

C:\Program Files\Microsoft Visual Studio 9.0\ReportViewer.

I use SysInternals Process Monitor to find where VS was looking for the containing file.

The assembly may exist but in a place not seen by the app. Use filemon / procmon to find out where your app is trying to load the assembly from and you will have a clue of what's going on. Also make sure the assembly version matches as well.