Excel formula changes to a constant

[Alon K]

Hi,

I am having a problem entering a formula (and keeping) a formula in a
cell in one of my sheets.

I have a formula entered into a cell as follows:

=INDIRECT( "F" & (Tool!$G$4 + 1))

The purpose of this formula is to retrieve a cell value from column
F#. Namely cell G4 in my 'Tool' sheet contains the cell link to a drop
down box contained in column F on my sheet. So for example, say column
F holds the following starting from F1:

Names
Jack
Andy
Mark
John

Then the listbox will contain this list (aside from name). Now say I
select Andy from the listbox, then G4 in the Tool sheet will have the
value 2. So the formula above should calculate to INDIRECT(F3),
namely, Andy. It does this correctly when I type in the formula to the
cell and press enter, unfortunately, it only keeps this the value and
the formula underlying this is removed!

To add to the baffle, I have the same exact thing set up in a
different cell, and that cell works fine and keeps the formula.

How can I fix this issue, I would like to set it up so that the
formula sticks.

Thanks,
Alon