Asus PG 221 self contained speaker/subwoofer problem---need help

Hello all!

I bought the referenced monitor for our home and have a question for those more knowledgeable than myself (it won't take much!).

I have a Dell XPS M1710 laptop attached to a docking station (port replicator). The docking station has a single stereo female port. I have attempted to connect the monitors speakers via a "Y" connector between the laptop/dock mini port via 2 RCA plugs to the monitors speaker ports. This does not appear to work. I have checked and double checked the volume levels and all connections and find no obvious problems, but still no sound. I have 2 external laptop speakers which test fine with the dock sound port. 

Anyone familiar with the PG221?

 AlSO: this link shows the input ports (including audio) for the PG 221 monitor:
http://www.hothardware.com/image_popup.aspx?image=big_pg221_6.jpg&articleid=1042&t=a

Any suggestions would be appreciated!

Thank you in advance!

Jim