mpi failed using Intel sample code

Hi,

I have installed intel parallel studio xe cluster edition 2016  on HPC environment.

All compilers are working fine.

when I tried to execute the following commands:

#mpirun hostname 

#mpirun  --machinfile hosts  hostname

It executed successfully returning all nodes' hostname

And I compiled the following sample <Intel_DIR>/compilers_and_libraries/linux/samples/en/mpi/test.c

using the following:

#mpiicc test.c

and execute the following command:  

#mpirun a.out

#mpirun --machinfile hosts a.out

but I got the following error:

HYDU_create_process (../../utils/launch/launch.c:622): execvp error on file a.out (No such file or directory)

HYDU_create_process (../../utils/launch/launch.c:622): execvp error on file a.out (No such file or directory)

HYDU_create_process (../../utils/launch/launch.c:622): execvp error on file a.out (No such file or directory) 

I wonder what might cause this error

Appreciate  your help.

Thanks