Currently Being ModeratedFeb 13, 2013 6:24 AM (in response to arc21)
If the initial iTunes Match scan, match and upload process is not finished in iTunes you may not see all the music in your iTunes library on the iPhone yet. Let the process finish in iTunes before activating the service on the iPhone.
Also, make sure the tracks in question are eligible for iTunes Match. Even if they are not "matched" to tracks in the store they will be "uploaded" as long as they meet certain criteria: over 96 Kbps, under 200 MB is size, do not contain any DRM.