Need Max(Cell Range) to stay the same

I play a war game and rather then try and do a lot of math in my head, I'm working up a spreadsheet I can pass around to my friends that can be easily updated to show the best unit to use in battle for attack and defense. I'm having a little trouble with my function. As follows:

Column A = Names (User Input)
Column B = Attack (User Input)
Column C = Defense (User Input)
Column D = Current # of Unis (User Input)
Column E = Output Value of X (will be locked awaiting function)
Column F = Output Value of Y (will be locked awaiting function)

Now my function looks like so:
=IF(MAX(B4:B10)=B4,VALUE(D4),"Don't Use") - works fine.
Unfortunately, when trying to auto fill down I get:
=IF(MAX(B5:B11)=B5,VALUE(D5),"Don't Use") - Does not maintain MAX(Cell Range) when auto filled or "Insert Row" feature is used.

I've even tried setting up 2 or 3 rows to show the cell that the MAX(Cell Range) is not changing and then auto-fill down but it still begins to change the the cell range.

i need the function to keep the same MAX(Cell Range), while verifying weather or not to output the Column D value or "Don't Use Value" so that when they use the "Insert Row" feature, it will update the proper MAX(Cell Range). I can do it all manually, but I'm trying to avoid a billion questions on how to manually update the excel ranges. any tips are appreciated.

thx.

Ah! Ty so very much. I'm limited and you just made me a little smarter! You're getting helpful points for thi1 1! Good Job and ty again.

Have a look at XL help about absolute and relative references ( and the use of the F4 key) for more info