knitting shut of surfaces

hey,

this is the first time i'm making a mold in solidworks. I stranded at the point of making the two mold parts (see figure)

It says that it can't knit the sheets together, maybe it's because I deselected the Knit command in making the Shut off surfaces. I did that because it told me there that It couldn't knit it there as well:

Maybe some of you immediately see the problem, that I'm too inexperienced to see?

thnx!

Jip Warendorf

SolidworksPlastics And Mold Design