Problem with formula in checkbox.


I have a formula in a cell check box:

=IF(COUNTIF(b3:b4, true) > 0, true, false)

It works great, but when you click on it, the formula is removed. It can be pressed accidentally, so I would like to protect myself.

Nothing checked.^|^

Only Monday3 is checked, and also Monday2 checked automatically. ^|^

I checked Monday2, and nothing else ^|^

Monday2 not working after checking(((((^|^