I worked on this issue for a few days. Installed all packages, modified web.config and still had the same problem. I finally removed
<assemblies>
<add assembly="Microsoft.ReportViewer.Common, Version=12.0.0.0, Culture=neutral, PublicKeyToken=89845dcd8080cc91" />
</assemblies>
from the web.config and it worked. No exactly sure why it didn't work with the tags in the web.config file. My guess there is a conflict with the GAC and the BIN folder.
Here is my web.config file:
<?xml version="1.0"?>
<configuration>
<system.web>
<compilation debug="true" targetFramework="4.5" />
<httpRuntime targetFramework="4.5" />
<httpHandlers>
<add verb="*" path="Reserved.ReportViewerWebControl.axd" type="Microsoft.Reporting.WebForms.HttpHandler, Microsoft.ReportViewer.WebForms, Version=12.0.0.0, Culture=neutral, PublicKeyToken=89845dcd8080cc91" />
</httpHandlers>
</system.web>
<system.webServer>
<validation validateIntegratedModeConfiguration="false" />
<handlers>
<add name="ReportViewerWebControlHandler" preCondition="integratedMode" verb="*" path="Reserved.ReportViewerWebControl.axd" type="Microsoft.Reporting.WebForms.HttpHandler, Microsoft.ReportViewer.WebForms, Version=12.0.0.0, Culture=neutral, PublicKeyToken=89845dcd8080cc91" />
</handlers>
</system.webServer>
</configuration>