Using icon sets with relative references
 

I am using Excel 2007 in the Vista OS.

I am trying to use conditional formatting with an icon set in a column but
Excel will not allow relative references.

Example:
A1=10 min
B1=20 max
C1=30 oh
D1=a formula { =IF(C1=0,B1,(B1-C1)) }

The condtional formatting of D1 would be:
if the value showing in D1 is B1 the cell would show a red 'X',
if the value showing in D1 is <A1 the cell would show a green 'check mark',
and if the value showing in D1 is between the values in A1 and B1 it would
show a yellow 'exclamation point'.

I can get the D1 to do this but when I try to copy the formatting down,
cells below (D2:D12) all show an absolute reference to the cells in row 1.

Is there a way to overcome this absolute referencing in Excel 2007? I have
tried to delete the absolute in the formula itself in the conditional
formatting dialog box but Excel returns an error and will not allow it.

My apologies if this question is not as clear as you need it to be. This
problem has me very muddled at this time.