How to use extractfeat? I am working on a script on bash linux to get the CDS (coding sequence) of a gene using extractfeat by EMBOSS. It gives me the error: Warning: No sequences written to output file

I am unsure if my syntax is right, but this is what I have: 

extractfeat inputFile outputFile -type CDS
Perhaps,removing introns (if it is a higher eukaryote)

extractfeat tembl:x65921 -type CDS -join 


It is difficult to know without knowing the gene. 

BTW NCBI's Entrez "efetch" will do essentially the same thing, but its more complicated