There are a few formulas which I need help on but the first formula I need is to count invoices within the month but NOT if the word "refund" is displayed in the corresponding cells of column J (J18:J80) or if the word "Paid Acc." is displayed within this same data range (J18:J80)

I'm guessing the formula will be a sumproduct but I'm not familiar with these and have tried to play around with it but cannot seem to get a proper value returned.

The formula which is currently being used is a countif formula as follows:

=SUMPRODUCT((B18:B80<>"")*(J18:J80<>"PAID ACC."))

Any help would be grately appreciated.