I am trying to create a mold tool for a part I have made for a project. I have tried various methods but am completely out of ideas. I have created the parting line and made a parting surface using the ruled and planar surfaces but when using the Tooling split feature i get "cannot knit sheet together". I have knitted the core and cavity fully and have knitted the parting surace, not to each other.

Any advice would be great as i'm now clueless.

Thanks