Serato DJ lite not playing music from SB3

I do not hear any audio from Serato DJ lite, however I hear when some other audio source is playing.

For example, my ddj sb3 is connected to my computer via USB. It lights to show that is connected. The buttons on the controller actually control Serato DJ Lite. However, I have the RCA outs going into 1/4 inch ins of my monitor, and no music is coming out. 

What's weirder is, when I go to play music somewhere, let's say youtube, audio is present.

Does anyone have any idea on what may be the issue. I just want audio to play from Serato DJ Lite