Conditional formula based on difference of two other cells

[excelproblem101]

i have a sheet with values in Column D and E

Now, they enter values in E45 and E36
Afterwards, they enter a value on D48 (They should calulate the difference of E45 and E36
The conditional formula should make the cell D56 red if they value they enter is not equal to the difference of E45 and E36
I have the following formula: =$D$48<>$E$45-$E$36

Now the format is only working if I have a formula in D48 with =E45-E36
But they need to enter the value.
I tried to change the formula to =D48<>ABS(E45-E36)
But still no luck.

Please assist?

 

[Fluff]

In what way is that formula not working?

 

[excelproblem101]

The conditional format is not working.
So it is not making the cell fill color red if the difference of E45 and E36 is not entered in cell D48.

 

[Fluff]

What are the values in those 3 cells when it doesn't work?