Problems with channel insert 2?

[noiseinurhead]

Hello,
I'm experiencing some kind of a weird problem,
I've hooked my tuner like described on the vh4 manual in the send of channel insert 2 with a shorted jack in the return.
Sometimes it works just fine and other times I can hear a lowered signal while I'm tuning coming out of my cab...
Is Someone as experienced that kind of thing?
Thanks for helping me solve this problem...

 

[Cro]

I've had the same problem. I have no idea how to fix it.