Formula not working when counting months

[Quinton]

Hello

I have the following dates in 2 cells:
18-12-09 and 17-05-11

I am using the following formula the count the months difference between the 2 dates:
=(MONTH(J68)-MONTH(I68))

The result I am getting is:
-7

I should be getting a result of:
17 (I think).

It is not realising that there are differeing years as well?

Can anyone please help??

Many thanks in advance

 

[Sektor]

=DATEDIF(I68;J68;"m")

 

[Quinton]

Many thanks, but the formula did not work. It may be because the 2 cells are referencing another worksheet?

Here are the formulas for 1 of the cells:

I68
=LOOKUP(2, 1/((Sdata1!$A$1:$A$1000="Chestnut Grove\")*(Sdata1!$B$1:$B$1000="Plot 05")),Sdata1!$C$1:$C$1000)

That data is also using another formula:
=IF(Sdata!C37="<empty>",TODAY(),Sdata!C37)

The data stored at "sdata!C37 is:
18/12/2009

Hope this helps?

Cheers,