Hi,
Check pricing procedure first.
Is it same for internal and external vendor. This is decided by the schema group maintained in the vendor master.
So check schema group in vendor master and for tht schema group wht is the pricing procedure maintained in the config.
And conditions maintained in the pricing procedure , check the condition types are manual or automatic. Manual means you have to select and enter the value.
Automatic conditions will have access sequence maintained and the conditions record maintained which will populate in the pricing procedure based on the condition record maintained .
Thanks,
Ravi