Trouble Transferring Music!!

[Milli16]

Everytime I connect my droid to my PC to try to transfer music to the phone I can't. I go to the my computer option on the PC and try to open the Removeable Disk D( which my droid is in) and it always says "Please insert disk into Drive D". The phone says its connected and the PC gives me the option to safely remove my phone. I even installed HTC Sync in order to solve this dilemma but nothing has worked! Can anyone give me suggestions on what to do? I really want some music on my phone

 

[Vitticeps]

Did you pull down the notification bar and click on "USB connected" then click "Mount"?

Just plugging it in doesn't get you there.