cufft - fft & ifft

hi everyone:)

I’m new in Cuda programming and now I’m working on convolution. I wrote cuda code and after testing I got suprisingly result (length of table 2^n):

n=5 fft signal and fft filtr ok, ifft not
n=10 unspecified driver error
n=100 fft signal ok, fft filtr and ifft not
n=1 000 fft funkcji and fft filtru
n=10 000 fft signal and fft filtr ok
n=100 000 fft signal and fft filtr and ifft ok
n=1 000 000 no effect
n=10 000 000 fft signal and fft filtr ok, but drivers die :P

does anyone have any idea why it is that? :)
thx for help:)

take care:)