Can't run CUDA program

I have installed CUDA 7.5 on Ubuntu 14.04. After installation when I used nvcc -V I got
nvcc: NVIDIA ® Cuda compiler driver
Copyright © 2005-2013 NVIDIA Corporation
Built on Wed_Jul_17_18:36:13_PDT_2013
Cuda compilation tools, release 5.5, V5.5.0

Than I compiled a program which created a.out file but when I tried to run that file using “./a.out” I am getting “cudaSetDevice failed! Do you have a CUDA-capable GPU installed?addWithCuda failed!

CUDA is probably not installed properly.

You say you installed CUDA 7.5 If it were installed properly, the reported version would not be “release 5.5” but “release 7.5”

If in doubt, start with a clean install of the linux OS, and follow the instructions in the linux install guide carefully.