WriteProcessMemory ERROR_PARTIAL_COPY 299

Question

I am trying to write to the memory of another process, I open it with permission 38h (VM_OPERATION, VM_READ, VM_WRITE), then i use VirtualProtectEx with permission 4h(PAGE_READWRITE), but i also tried PAGE_EXECUTEREADWRITE - same error later.

Then I invoke ReadProcessMemory, and successfully read out the value of a fix address. But as I try to write to that address with WriteProcessMemory i get the Errorcode 299 - ERROR_PARTIAL_COPY.

Does anyone know how to solve this?

EDIT: SOLVED - didnt pass the buffer to write as a reference but as a value