Hello .net dev,
Only the toolbox items for the newest version of Telerik Reporting installed on the machine will be available inside the Visual Studio Toolbox.
In case you have installed Q1 2015 SP1, you won't be able to use the VS Toolbox items of Telerik Reporting Q2 2014, which is the version shown in the attached toolbox.png
In order to design older version reports (e.g. Q2 2014) you need to run the Upgrade Wizard
and upgrade the reports to the newest version of Telerik Reporting installed on the machine.
After you are done with the modifications, and if this is needed, you can downgrade the reports to their original version again using the Upgrade Wizard