Why I can't use the resulted gpumat from cv::cuda::Convolution::convole()?

edit

cv::cuda::GpuMat d_b1, d_b2, d_b3, d_addb;
cv::Ptr<cv::cuda::Convolution> convolver1 = cuda::createConvolution(); 
 convolver1->convolve(d_bdouble, gk1Mat, d_b1);
 convolver1->convolve(d_bdouble, gk2Mat, d_b2);
 convolver1->convolve(d_bdouble, gk1Mat, d_b3);

cv::cuda::add(d_b1, d_b2, d_addb);  // I got the error in the follwoing line

I have no idea why this happening. Can someone please help me.