Regarding Shared Memory Allocation

Hi,
Iam working on wlan device driver for pci interface.whenever i
try to allocate memory using NdisMAllocateSharedMemory its getting
failed, and here is the code that iam using to allocate memory.

*PUCHAR temp_vir_addr;
NDIS_PHYSICAL_ADDRESS temp_phys_addr;
NdisMAllocateSharedMemory(pAdapter->AdapterHandle,memory_size,FALSE,
(PVOID)&temp_vir_addr, &temp_phys_addr)
*
where memory_size is some 380.

can someone please suggest me some solution.

Thanks & Regards
ajay kumar v