POP Record purchase invoices option to Save and Retain code

SUGGESTED

Within POP Record purchase invoices there is an option at the bottom of the screen to Save and Retain code - but it is greyed out and we cannot access it?

There is the same option within P/L when recording manual invoices and this works ok. Unfortunately we record a few dozen manual invoices per month and a few thousand purchase order generated invoices per month and this is really time consuming for data entry - our software provider cannot help. Any help with a way around this issue would be appreciated.