Excel tells my formula in new name in name manager has a problem

So, I've been following a guide on how to create an invoice with excel on youtube (can't show you the exact video cause my account is fairly new, but it's the most famous one by the youtube channel: excel for freelancers)

At around the 14 minute mark he says to put a formula in the'refers to' bar, namely the following formula: =OFFSET([tabname]!$A$2,1,,COUNTA([tabname]!$A$2:$A$999)-1,1
If I type the EXACT same thing in my formula bar it says that there is something wrong with my formula. I've noticed that I'm using a different excel than in the video, but the video is not THAT old

Feeling I'm missing something... But not sure what
Anyone know what to do? Thanks in advance