Problem opening files with grib extensions

[Giannakos Apostolos]

Dear list

I have downloaded from ecmwf a grib file that ends with the string grib
like retrieval.grib When i am trying to create the ctl file with the
command:

   ./grib2ctl.pl retrieval.grib >retrieve.ctl

it gives me an error report like the one below

   found unidentified data
   Big problem:
  either retrieval.grib is missing or not a grib file
  or wgrib is not on your path
I am sure  that wgrib is in my path and i have retrieval .grib because when
i am using files with extensions .grb and then run the command to create
the ctl file it doesn't give me error.

For a reason doesn't recognises files with grib extension
Does anyone knows what should i do to open the  files with the extension
grib.