Can't put Icons on Second Monitor

All of a sudden I cannot move icons from the desktop on my main monitor to the desktop on my secondary monitor. There's no problem putting application windows on the second monitor but icons just slide back to the main monitor's desktop. I tried restarting and that didn't solve it. Has anyone seen this and have a solution? I'm running a late 2012 Mac mini with Mavericks 10.9.2.

Thanks,

-= Ken =-