How to add a warning message when no value is obtained in condition type for taxes in purchase order

[alvaro_provencio]

Hi gurus, 

I have been requested to add a condition type for tax determination when creating POs, this condition type has a sequence of 5 condition tables and I need to show a warning message when none of the tables have given a result (no condition has matched) and therefore the tax hasn't been calculated.

I have tried to search in spro in case it can be configured somewhere but haven't found anything, am I missing something? Does anyone knows a customer exit or BAdI to add this message after the validation?

Thanks, 

Álvaro.

[raymond_giuseppi]

If code is required, look at the methods available in BAdI ME_PROCESS_PO_CUST such as PROCESS_ITEM.

[raymond_giuseppi]

Why do you require a 'Warning', relations between the Purchasing Department and the Finance Department ?

[alvaro_provencio]

Hi Raymond, thank you for your reply, I have checked the BAdI and I can work with it, but I am facing another issue. If I specify the message as an error, the message appears and everything works fine, but if I specify it as a warning, It doesn't show. Answering your question, this is the requirement I have been assigned, it seems feasible despite this last issue