Flashing tape leaking

[Elementalist]

I have put up a (corotherm) polycarbonate roof and used this flashing https://www.diy.com/departments/roof-pro-grey-flashing-tape-l-10m-w-200mm/1932704_BQ.prd along the top of the roof to the wall and also a less wide version to tape where it goes against a wall. I applied it on to a painted rendered wall and used a roller to press it down as per instructions I have read. However it leaks whenever the rain is any sort of strength, pretty much all round.

Not really sure where I have gone wrong as was just trying to follow internet instructions as best as possible. So hoping someone could give me some suggestions?

 

[freddiemercurystwin]

You've gone wrong by fitting something inappropriate, it should have a proper flashing chased into the render.

 

[tell80]

OP,
If you post a couple of pics maybe it will help?

 

[Elementalist]

Thanks, going to go with proper flashing chased into the render. That's how it was done in the previous incarnation, just the manufacturer installation video showed it being put up with tape around.