Roof Mounted Cargo Carriers I Have A 05 Pontiac Vibe. I Have The Basic 2 Parallel Roof Racks. Can I Use A Cargo Carrier? Need Crossbars?

I have a 05 pontiac vibe. i have the basic 2 parallel roof racks. can i use a cargo carrier? need crossbars? - roof mounted cargo carriers

I have a Pontiac Vibe. Mobile IM and you want to use a carrier. I have Core 2 bars, but not the crossbar. Can I create an airline to. I get the crossbars? Where can I buy?