Javis Grass Mats

[enfield250]

Hello!
I'm new to this forum, I'm building a small N Gauge layout in my conservatory.
I bought two Javis mats ballast and meadow grass.
I had no problem laying the ballast mat but, the grass mat is totally different.
The mat is very stiff and difficult to trim to size.
A few years ago I bought a grass mat and it was very easy to lay.
I just spread PVA on the surface to cover laid the mat over pushed it into the crevices and it stayed.
This one doesn't want to mold to shape.
I'm using PVA on the back of the mat and on the area to cover.
Am I doing something wrong or should I have bought something else to cover the hills and fields?
Cheers,