General wrote...
Try this sir:
Indirect("SHEET1!A")+indirect(O4)
to get the idea.
....

What idea do you believe the expression above would convey? How to live
with error return values? Syntactically, SHEET1!A could *only* be a
worksheet-level defined name, and, semantically, only one referring to
a literal range.

"stephen.reading100" wrote...
....
I can reference a cell with just the row data from another cell.
INDIRECT("SHEET1!A" & O4)
But if I want to reference a cell using both row and column data from
other
cells? Something like this, but this doesn't work.
INDIRECT("Sheet1!R4 & O4")
....

OP should try

=INDIRECT("Sheet1!"&R4&O4)