The other sheet was probably opened first and reset calculation to manual..
Check it's options.

--
Don Guillett
SalesAid Software

"Chris" wrote in message
...
Today a user experienced a situation where a spreadsheet that he had open
did
not calculate properly. The auto-calculate function was turned on, but
when inputs were changed, the final results would remain unchanged until
he hit the "super-calculate" function (control-alt-f9). He would then
watch the final results change.

He had another excel file open at the time (Note: these files were not
linked). When he closed this file, the problem corrected
itself.