If statement is giving too many arguments error

I have an excel formula where I have to get the difference of the days between two columns which have day/month/year date. The formula works fine as long as the difference-column does not encounter a blank date in one of them two; basically if one of the two dates column is blank the formula displays weird numbers like 344440.

I wanted to solve my problem with an if statement which works fine for one column (column S, one of the column with dates which could be blank), but gives me all sorts of errors when I try to input that column Q could also have a blank cell (other date column).

Thank you guys.

So far I have tried:

=IF(S14= "","",IF(Q14 = "","",NETWORKDAYS(Q14,S14)),NETWORKDAYS(Q14,S14))

or

=IF(S14="","",NETWORKDAYS(Q14,S14), AND(Q14="","",NETWORKDAYS(Q14,S14)))

Also tried iferror/ifna, no luck so far.