airmon-ng drops interface

Hello! I am having some wierd problem.
When I run airmon-ng on my wifi interface I get this:
[code]
[eric@heaven ~]$ sudo airmon-ng start wlp0s29f7u1u2
No interfering processes found
PHY   Interface   Driver      Chipset

phy4   wlp0s29f7u1u2   rt2800usb   Ralink Tec...