slow draining from shower tray

[pete the non plumber]

hi guys and girls need a bit of advice from a plumber or that, i fitted a new low shower tray and its draining very slow i have to switch off power shower to stop water getting close to the top of tray all i changed was tray it came with its own waste trap and connected it with flex pipe as draining point was other end from previous now when i screwed waste to tray the hole in the trap is half covered is that my problem or is it the flex pipe coming from the trap ? ps this is with out chrome lid on trap hope this makes sense as i am a sheet metal guy and i know some silly questions ii get asked for metal work lol i have a picture but not sure how to post it

 

[ShaunCorbs]

Is the waste running down hill and not up ?

 

[novice plumber]

I have the same issue, my new shower drain off is very slow

 

[Deleted member 120897]

I have the same issue, my new shower drain off is very slow

Did you do the same as OP?