Trying to configure brand new PO workflows but getting error messages

Hi All, 

I am quite new to the Dynamics 365 world as my company has just acquired this platform. 

I am trying to configure new PO workflows for our offices in France. I have configured a brand new workflow to test this out. Once completed I have tried raising a PO but I get the following error: *One or more accounting distributions is missing a ledger account. Use the Accounting distribution form or the Posting profile to update the ledger account.*

I am not sure if this is a configuration that has to be set up under Stock management > Setup > Posting or is something completely different I should have done before starting the workflows? 

Thanks a lot!