Requirements are not fulfilled for condition PR00

Hi Experts,

We want to use Free Goods item category TANN.

Also, we change the PR00 in pricing procedure RVAA01 to 'Not Required'.

But when I create a SO item with free goods item category, the currency cannot be changed from USD to other currency.

And the system info showed up"Requirements are not fulfilled for condition PR00".

What this message mean?

Thank you

Alice