A co-worker is having concatenation issues. There are 2 workbooks he is
working with.

Book 1-Sheet 1
A10-A12= individual lines of data which need to be "combined into...

Book 2-Sheet 1 in cell A10

Please correct me if I am wrong. In Book2 Sheet1 cell A10, he should put
the following...

=CONCATENATE([Book1]Sheet1!$A$10,[Book1]Sheet1!$A$11,[Book1]Sheet1!$A$12)

On a test workbook at my workstation, it works fine, however, when I
demonstrated this to a co-worker, he attempted, and text shows for a brief
second, then disappears and the formula still shows in the formula bar??

All suggestions are welcome!

TIA,
Sandi