Report with conditionnal formatting issue

Hi everyone,

I have made a report based on a crosstab query (based on a table) which
looks like this:

------------------------------------------------------------------------------------
Head1 Head2 Head3 ...
Col1
subgroup1 Date1 Date2 Date3
subgroup2 Date4 Date5 Date6
subgroup3 Date7 Date8 Date9
...
Col2
subgroup1 Date1 Date2 Date3
subgroup2 Date4 Date5 Date6
subgroup3 Date7 Date8 Date9
...
Col3
....
------------------------------------------------------------------------------------

The crosstab query is based on a table which looks like this:

------------------------------------------------------------------------------------

[rec1] [rec2] [rec3] [rec4] [rec5]
---------------------------------------------------------------------------
Col1 Head1 subgroup1 Date1 percent1
Col2 Head3 subgroup3 Date2 percent2
Col3 Head12 subgroup4 Date3 percent3
Col4 Head7 subgroup4 Date4 percent4
.... ... ... ... ...

------------------------------------------------------------------------------------

My question is how to turn the "Date" fields to red (in the report) when the
percent value (column rec5 in in the table) is less than 100%?

The main issue is that the "percent" field is not a part of the report (and
does not have to appear OR be visible) and neither of the crosstab query.

Thank you for your help !