program of pcie data transfer

newly，i found when transfering data from pc to pcie board via pcie,the data is not in proper order e.g. the data in pc driver is 0 1 2 3 4 5 6 7,then in pcie board the data maybe 0 3 1 2 7 4 6 5.i use the pcie ipcore example for my design.who can help me?