Conditional formatting traffic light formula

I have 3 columns; Start Date, Target Date & Actual Number Of Working Days for a project. I want to condition format column C so that if it has over-run the target date it should show the red traffic icon, if it is spot on the target date it should show the amber traffic icon and if it is under the target date it should show the green traffic icon. If there is no start date the rest of the row should be blank. In this case I want the conditional format to remain blank. Please note I want to see the traffic icons and also the number of working days as well on the same cell, I don't want the traffic light icons to replace the numbers. So in the example below, C1 should be green, C2 should be red, C3 should remain blank, C4 should be amber. Thanks for any help I get.

	A (Start Date)	B (Target Date)	C (Actual Number Of Working Days)
1	2/6/14	10/6/14	10
2	2/6/14	10/6/14	5
3
4	2/6/14	10/6/14	7

Hi nflsales, thanks for your help. Unfortunately when I put your conditional format formula into my spreadsheet it doesn't seem to work. I don't know if it is because on my sheet the working days column there is actually a formula which produces the number of days.

The columns I am interested in are EQ, ER & ET.