Excel Mobile - strange behavior

I am using Excel Mobile on my HTC for time tracking. I think it has
some strange behavior. I am using time formats and often the last
line (date) in my excel sheet shows a #VÆRDI! where VÆRDI is Danish
for VALUE. When I then later adds a new line the cell with #VÆRDI!
suddenly shows the expected value? Also sometimes everything is okay
first time I add a new line but when I edit e.g. 16:00 to 15:00 and
back to 16:00 then suddenly excel can't show the duration and again
says #VÆRDI!.

Any help would be nice.

--
Associate Prof. Ph.D Torben Knudsen Mobile : (+45) 2787 9826
Section of Automation and Control, Email : tk@es.aau.dk
Department of Electronic Systems,
Aalborg University
Fredrik Bajersvej 7
DK-9220 Aalborg Ø
Denmark