Prefill print form

[Justas]

Found answer here:

Pass parameters to SSRS report form

The GUID (the “c33b3dbb-dd86-47ec-a0dc-b07d2fa5caab” part) is unique to your system. You need to find that control’s GUID, and adjust the code to use it. In customization mode, click on the control whose GUID you need to know, then in the developer window, go to the properties tab and the GUID will be listed.