Who says it is not possible ?
I have just given a workaround. If you want to use your procedure, you can check the below.
I think your condition table is still under not accessible.
Go to M/07, Select the Access sequence, then click on the Access, then select the condition table and then press Fields. You do not need to do anything here. Just go back and try to create PO again.
You will be able to see the condition type in PO - Condition tab.
If you are still not able to see the condition type, then please press the analysis button and try to find the error why it is not accessing the condition record.