conditional formatting not working

I have a subform that displays a datasheet. I want to change the background

color depending on a value in one of the fields. I CAN make this work by 
using Conditional Formatting from the ribbon. My problem is that I want to

tweak colors, etc and would like to do this through vba. I have put this
code 
in Form_Open for the subform (declarations left out for simplicity):

Set objFrc = 
Me.subfrmData.Controls("Subj").FormatConditions.Add(acFieldValue, acEqual,

"Math")
    With objFrc
        .FontBold = True
        .BackColor = RGB(255, 0, 10)
    End With

Compiles without error, I can step through and see the values being
changed 
properly....but no change in the display.

Suggestions? I'm pretty sure it's something easy...am ready to be 
embarrassed for myself if I can just get this last little tweak
working..... 
LOL

Thanks in advance.

zkmoon