RTD BUG ON Excel FUNCTIONS?! FOR HELP

[chrisben]

Hi,

I created a RTD server which will get live data from a
data server constantly (by a middleware). It seems work
well until the user want to use some build-in functions in
Excel.
For example, if I have RTD link at cell A1 and I would
like to do something like =A1+A2 in cell A3, it will work.
However, if I do something like =sum(A1:A2), it does not
work at all. Same for other functions.

This does not make sense to me at all. Is this a bug of MS
Excel RTD technology? Does anyone else have the same
problem? Any solutions?

Thanks a lot for the help

Chris