Why aren't my itunes songs showing up in my iphone?

I'm trying to sync my playlists… There are songs on my playlist in itunes that won't sync in the playlist on my iphone… They show up as gray with a dotted circle on the left… I bought them on itunes, so it can't be that is the issue… Please help

I thought songs were for ipod touches?

As for the first answer-er, I'm sorry but get a brain XD
As for your problem, this is iTunes way of saying that it can't find the original music file.
Think of iTunes as a cd player in your house with all of your music sitting next to it. The cd player plays the music, but the music isn't actually on the cd player.take away the cd, and the player will not know what to play. Basically, you moved the file from where iTunes thought it was originally, and it doesn't know where it went (you removed the cd from your hypothetical cd player and lost the cd).

So to fix it, double- click a song that has a grey circle to try and play it. Because iTunes (the cd player) doesn't have the file (cd) to play, it can't play it, and will give you a message that says something like "iTunes can't find the original file. Would you like to locate it?" Of COURSE you want to find your missing cd! You payed good money for it! This is the hard part. What you're going to have to do is open up all the folders on your computer until you find the file (cd).it will probably be named after the song that you're missing, and the album name as well as the artist (i.e., if you're missing the song x, written by y, in the album z, it will probably be named something like y, z- x). Double- click that. If it is the right file, iTunes will accept it, and will ask you if you want it to locate the other files in the same location.click yes, as the other songs are probably in the same place. If you're lucky, iTunes will find all of the songs. If you're unlucky, you will have to repeat this process for every single song. After doing this, all of the songs you have check marked in your iTunes library will go onto your iPhone!

Sorry for the super long answer, i tried to walk you through every last step.

Https://discussions.apple.com/index.jspa
ask question on that site and they will give you step answer

It means that the itunes can't find the original music file.
Just find the original file then add them in your itunes then sync your iphone.