If you get this error:
"Could not load file or assembly 'Microsoft.ReportViewer.WebForms, Version=18.104.22.168,"
You need to run this file on the server:
The ReportViewer control redistributable is a self-extracting file named ReportViewer.exe that includes an .msi and other files. You can find ReportViewer.exe at the following location: C:\Program Files\Microsoft Visual Studio 8\SDK\v2.0\BootStrapper\Packages\ReportViewer\ReportViewer.exe.
Found the solution here:
Deploying Reports and ReportViewer Controls