IF statement with Right, Len, and Concatenate

I am using Google sheets and not sure why I can not get this to work but I think I have a bracket off or syntax not quite right.

I am trying to parse out a URL and get the last 3 letters to compare to in my IF statement. If the 3 letters match png then do something if not do another.

=IF(RIGHT(E2,LEN(E2)4)=".png",CONCATENATE(F2,G4), CONCATENATE(F2, G3))

The URL comes in through a formula into the cell E2 using this:

=ImportXML(B3, "//meta[@property='og:image']/@content")

I am not sure if that has something to do with it or not but I have found I need to test for .jpg and .png because not everyone uploads .jpg all the time causing things to break on my feed.

Here is my google spreadsheet