This is my first post here, and i hope it doesn`t sound full ridiculos (i try to write in english the best way possible, however

i recently bought a kaoss pad mini (mini-kp), and i really like to play around with it, and since the (bass-) synths sound quite good for me, i was thinking about in feature them in my music productions.
so far so good.
i connected the line out of the mini-kp with a Y-cable to the line input of my audio interface. Ableton shows, that there is a signal, the interface does the same, but no sound comes from my monitors. I tried it with the 2 inputs, nothing.
I also checked the Sound Preferences in Ableton.
i am using this interface, and my monitor speakers are connected to the line out of it.
(i am using a tascam us-122L SC by the way:
https://www.google.at/search?q=tascam+u ... 39&bih=722)
can somebody please tell me whether this is utter bullshit, i am trying to do here?
It sounds quite logical, but i dont get it anyway

Thanks in advance!