Are you using condition table 05 in access sequence CP05?
I hope 05 condition table for customer/material. Its used in sales pricing not in MM purchasing pricing (PO).
It can't be used in for access sequence in M/07.
Please use 018 condition table for material info record and 017 for material info record (Plant-Specific).
I suggest please use 0002 standard access sequence for condition type PB00.
Test the scenario.