Cyclone IV FPGA communicate with CPU by pcie

hello guys,
I use the cpu communicate with fpga by pcie and the cpu is the RP and FPGA is the EP.In RP i can read the EP vender ID , device ID , BAR mask and allocate pcie address for EP.but when i send data to EP, the EP cann't receive the data.What question cause this problem?
Please give me some help!
thank u very much!