Replying to Cany you tell if someone has viewed a text on the Droid?

Just got the HTC Droid and I was wondering if there was anyway to check to see if someone has read a text message you have sent them. With my last two phones, a little green check mark would appear when someone who also had Verizon read a message I sent them. If they had a different carrier than Verizon, it would just remain an arrow. I enabled to setting for "Delivery Reports" but when I sent a message to my dad who also has Verizon, there was just a little envelope with a green lower case "i" next to the messages I sent him and it never changed after he replied. Is there a different setting I need to enable or something?