No sound when opening the Juce demo VST GUI in reaper

My name is Damien and I’m evaluating the use of Juce to create some comercial plug-ins.

The juce demo plug-ins make do more sound when reaper open his GUI (
It works fine using vsthost (

Does anyone has met the same problem and find a solution ?
It may be a problem related to reaper configuration.
It seems that repear pause it self when it loose focus, it may be releated.

As it is my first post, don’t hesitate to tell if the content is apropriate or not, or at his right place.

Thanks in adavance.