CDO

I converted a netcdf to grb2 with

cdo -b F32 -f grb2 copy test.nc test.grb2

The values in netcdf file are single. During the conversion I got the following warning:

GRIB_API ERROR   :  unable to set double array codedValues (Unable to code a field without values)

Could someone write me how I could fix this error?

Thank you for your help in advance!