It may occur that a system planned purchase order remains in status 20 after releasing it.

E.g. below example, that also shows warning message “B”.

Open the line => at the bottom of PPS170/E, select the warning message and hit F1 or select the help text. It will give you a list of codes with more details for root cause.

After correction, being in edit mode, Actions - F16= 'Check errors' can be used and the warning message field will be updated.