The first thing I did was to make the formula in an empty sheet.
All good, no graph presented.
Then in C1 I write 1
then in D1 I write 2
I get a little line!!! Yes.
Then in E1 I write 3
eeeh, what happend. Now I have 2 lines: the first little line does n ot disappear.
In fact this little line stays forever. I have to delete it manually.
I use version 3.3.5 for excel2003.