Nothing wrong with the 'syntax' of the formula.

It looks to find a match to D6 (after being Trimmed) within column A of Account Detail.
If a match is found, returns a value from column F of Account Detail
If there is no match, it returns ""

In what way is it not working for you?
Do you get an error? What error?
Do you get the wrong result, what result DO you get?

I would guess it's just returning ""
Try removing the Iferror part, what is the actual error?

Can you attach a sample book ?