1) are you reading the chord diagrams correctly? I would've thought you'd know if your not.
2) are you trying to play along to the CD? In which case the song could be in a differnt key to the music you have.
3)Chords won't give you the tune of the song. My music theory isn't great so I couldn't tell you why certain chord sound 'right' with a particular piece of melody, so if you just play a string of chords, It won't bear a great resemblance to the tune, but you should be able to sing the song over the chord you are playing
Can I suggest a site like http://www.tabtalk.com which has loads of music ( mainly chords and lyrics) to lots of popular bands. See if you can get the hang of some of those.
Hope this helps.
John E