Formula to make it mandatory to fill in one cell if another cell has data in it

Hi,

I'm new to this and hoping someone can help me, I've tried to get my answer by viewing other posts but don't seem to be making any progress! I would like it to be mandatory to select an answer from the dropdown options in cell F8 if cell D8 has data in it.

I would like to do the same for the following:

F10 if D10 has data
F12 if D12 has data
F14 if D14 has data
F16 if D16 has data
F18 if D18 has data
I8 if G8 has data
I10 if G10 has data
I12 if G12 has data
I14 if G14 has data
I16 if G16 has data
I18 if G18 has data
L8 if J8 has data
L10 if J10 has data
L12 if J12 has data
L14 if J14 has data
L16 if J16 has data
L18 if J18 has data
O8 if M8 has data
O10 if M10 has data
O12 if M12 has data
O14 if M14 has data
O16 if M16 has data
O18 if M18 has data

If someone could help me out it would be greatly appreciated! Thanks,

Mark

Hi,

Thanks for taking the time to have a look at the problem I've got,

I have tried highlighting the cells, selecting Conditional Formatting, New Rule, then it asks me to select a rule type, I selected Use A Formula To Determine Which Cells To Format and typed in the formula but it hasn't worked.

Any idea what I have done wrong?

Thanks,

Mark

Thanks again.

One last question - is there any way to make an error message come up if they try to save it without filling in the field I want them to fill in.

So for example, they put a figure in D8 and E8 but then try to save it without selecting an answer from the dropdown in F8, can I make an error message come up telling them to fill it in?