solidworks tooling split cannot knit sheet together

I always have this problem when trying to do tooling split in solidworks ,
after having parting line , shut off surface and split surface when do tooling split it says cannot knit surface ,
i think it is about parting surface
so i have tried both creating parting surface through mold tools and manual surface with shut-off trim (i found on youtube)
but the problem continues .
i'm sure that i don't under stand it completely.

3 Answers

i have modified the split surface location it did create split tools but the core and cavity have no curves of the part

Here is an example of one way to split this part. Notice how the parting surface emanates From the part and Not Through it as in your example. The "Part & the Parting Surface" split the cavities.
Keep in mind there are Many Ways to Split this part in SW's, with practice you can master them.

Here are the steps to make this particular split. Mind you this is just an example, How To complete a tooling split in SW's.
I suggest you study the SW's Tutorials and the many YouTube tutorial's on the web.