Pps kar98k safety

I've recently purchased the pps kar98k and I really like the gun so far. The safety functions, but whenever I fire the gun the safety switch moves up and down, any suggestions how to fix it? Second thing I was wondering about is that when the safety is on there is 0 tension on the trigger is this supposed to be like this? I've never owned a gun with a trigger behaving the same way like the pss kar98k when on safe, so that's why i'm asking this silly question . Thank you in advance!