I'm having problems entering conditional formatting via VBA.

I realise that if a condition exists, that I need to modify it so I started
by adding 3 conditions to the range.
I'm using the following code, but it doesn't work.

Private Sub Worksheet_SelectionChange(ByVal Target As Range)
If Range("$K$6").Value = "Time" Then
With Worksheets(1).Range("$M$8:$N$8").FormatConditions( 1)
.Modify xlExpression, , "=AND(K8=0.1,OR(M8<K8*0.9,M8K8*1.1))"
.Font.ColorIndex = 3
End With
With Worksheets(1).Range("$M$8:$N$8").FormatConditions( 2)
.Modify xlExpression, , "=AND(K8=0.1,OR(M8<K8*0.9,M8K8*1.1))"
.Font.ColorIndex = 3
End With
With Worksheets(1).Range("$M$8:$N$8").FormatConditions( 3)
.Modify xlExpression, , "=AND(K8=0.1,OR(M8<K8*0.9,M8K8*1.1))"
.Font.ColorIndex = 3
End With
End If
End Sub

There's some very odd stuff happening. The condition formulae are being put
in place, but not acting as conditions.

This was all written into a new sheet, so there's no legacy
formatting/formulae anywhere.
If M8 is the active cell, the conditional formatting operates as expected.

M8 is red when the active cell is one of the following:
K1:K8
M1:M7

If the active cell is anywhere else, the font is black. It doesn't matter
what values are placed in K8 & M8.

K8:L8 are merged and M8:N8 are merged, but the same thing applies to M8 when
all the cells are unmerged.

I can't understand what's happening. HELP!

--
Ian
--