Why can't my tooling split knit sheets together?

Hello guys,

first at all - i'm new to this Forum, so please correct me if i'm doing something wrong with this post

I'm currently working on a mold-design Product (vacuu cleaner) and i'm getting frustrated over the last step of building a core and cavity with the tooling split. No matter in what different ways i've tried to create core and cavity surfaces, i can't manage to get my tooling solit to work...

I'll try to attach my solidworks.file and maybe one of you guys can have a quick look on it for me and explain what i am doing wrong so i can shut down this problem for future parts?

Thank you so much in advance,

Niclas

SolidworksPlastics And Mold Design