HTC Vivid says "No Music Found" on new 4GB MicroSD Card

I recently purchased a 4G MicroSD card to accomodate my music library on my Android phone.

As with my old MicroSD card, I place the new one in my phone, connected it to my Macbook via USB cable, and accessed the MicroSD folder. From there I dragged my desired music onto the folder and everything transfered completely fine BUT  when I look in my music app on my phone, it states “No Music Found” 

What is the cause and how do I fix this?

itunes default file type is AAC. andriod phone do not support AAC files. you will need to convert the music files to MP3 format then transfer them. 

here is how to conver the files

http://kb.sandisk.com/app/answers/detail/a_id/1129/kw/transfering%20itunes/related/1