I don't really see where you're trying to go with this, Bill. What's
the relationship between BU25 and CK24? Where does BU28 fit in to all
of that?

The first paragraph of the scenario is simple enough, and handled
(apparently) by the first IF function.

From the second paragraph I'm thinking you want something like:
=IF( ISBLANK( BU25), "", IF( ISBLANK( CK24), SL!E24, JL!E24))

But then you threw in the IF regarding BU28, and I'm lost.

I think you need to re-state your problem more clearly. What are all
of the conditions you want to check for, and what are the results you
want?

(It would help a lot to get out of the double-letter columns for
purposes of illustration; I'm confused by the multiplicity of letters,
alternate rows, etc. I'll try to deal with it, but it is a pain.)

Chris