cudaHostGetDevicePointer() not working?

Hi All,

I am using pinned memory in my kernel and declaring like :

and finally I get cudaErrorLaunchFaliure after launching that kernel. When I debugging in debug mode I get null value in x in function cudaHostGetDevicePointer() .

Could any one help why is it null?

when I wirte

I got the error cudaErrorPriorLaunchFailure .

What is the cause of that error? please help.