Respected dears, inside the mold creation, I used my own created parting surfaces instead of auto generated parting surfaces.

I also joined (knitted) these surfaces altogether to be selected under parting surface dialogue.

Now upon Tooling Split, i am unable to get core and cavity separated... and msg comes "Rebuild Errors...cannot knit sheets together"

I don't know how to overcome this problem, guide me please if someone can help easily...
Edu SOLIDWORKS 

as auto generated parting surface i don't want bcoz it is not perpendicular to the pull direction as can be seen