DRL Light Problem

I have a 1998 GMC Yukon SLE and I have DRL installed. Yesterday I noticed that the green icon for DRL that lights up on the dash is not on on to let you know DRL's are working. I have checked the lights and they are on even though the icon is not lighted up, I've checked the parking brake to make sure that its not partially engaged. Everything checks out ok but the icon is still wont light up like normal? Can anyone help me with this issue if possible?