PCIe driver using WDF: Cannot access memory value

Question

I am writing a PCIe driver using WDF, but I'm having trouble accessing memory values. Specifically, when I use MmMapIoSpaceEx to map Bar0 memory space to a virtual address with continuous length, I cannot read or write values to memory. The device has 64M length memory, and the Bar0 space is used for device registers. I have already checked the configure space, and the same device works fine on Ubuntu. Can anyone suggest a solution?