Cant split to core and cavity

Hello guys.I´m new in molding. I have a problem.I am unable to split core and cavity. It says ,,cannot knit sheet together,, . I spent 3 days to solve this but cant do it. Can anyone help me? Where is the problem ? Surfaces for core and cavity seems to be ok (for me). Everything is connected, no holes.

SolidworksPlastics And Mold Design