Can't get music on the phone

I opened up iTunes on my computer to get music onto my iPhone. I saw it connected and I authorized the computer on iTunes. I went to edit the playlist and when I tried to drag the already imported music into my iPhone's sidebar/list, it showed me a red X with my song count I tried dragging over like this:80.When I tried to drop it it did nothing. I tried right-clicking the songs and clicking "Send Songs to iPhone" but still nothing. I created a playlist and did the above but nothing. I even tried dragging the playlist itself onto the sidebar but nothing. I tried syncing the phone but nothing. Storage should be no problem because my iPhone is the 64 GB model and still has 32.9 GB available. Does anyone else have this problem and was able to fix it because I am all out of ideas. I appreciate any help I get. Thanks,

afchlam