SSRS for SharePoint - Trouble with parametrs

Hello! I have the proplem:  I have SSRS add-in for sharepoint 11.2.5569, SharePoint 2013. 

Sometimes when I enter parametr value and then press button to get report - report refresh's, my entered value cleared, and I need to enter again parametr value and press button to generate report.

I create video of this problem: https://youtu.be/Ln9VXy21Dvk

Please, let me know how to fix it! Thank's!