OK, so you know that your original formula was working, so that first VLOOKUP should be OK.
Focus on your second VLOOKUP (on the "OTHER" sheet). Try to write that one by itself. Once you get it working, then you can add it to the first one.
Note that if it is possible that one of the sheets might not have a match, you need to account for that (as that will cause the VLOOKUP to return the #N/A error).
You can do that with this structure:
Excel Formula:
=IFERROR(VLOOKUP(...),0) + IFERROR(VLOOKUP(...),0)
which will return a 0 if it does not find a match (instead of an error).
Note that I am counting on you filling in the details for the VLOOKUP where I show the ...
The point is to just show you the formula structures.
Since you were able to create the first VLOOKUP successfully, I trust that you know how to set them up.