problem with Xilinx OPB to OPB bridge

hello all, I'm building a system with EDK 7.1 on a virtex4 using Xilinx IP and soft processor Microblaze .i'm using 2 OPB bus in my design the first one is my mb_opb and there is another one (opb_2) who is link with mb_opb through an opb to opb bridge. My problem is there is no communication from my microblaze to my opb_2 ( no I/O from RS232 connect to opb_2). thanks for your answers.