htseq-count does not generate read counts as expected

Question

I have a .gff file which looks like below.

caffold1       GeneWise        mRNA    227302  283623  80.88   -       .       ID=Mnat_00001;evid_id=ENST00000360911;Shift=0;
scaffold1       GeneWise        CDS     227302  227498  .       -       2       Parent=Mnat_00001;
scaffold1       GeneWise        CDS     230150  230298  .       -       1       Parent=Mnat_00001;
scaffold1       GeneWise        CDS     233743  234426  .       -       1       Parent=Mnat_00001;
scaffold1       GeneWise        CDS     236092  236835  .       -       1       Parent=Mnat_00001;
scaffold1       GeneWise        CDS     238558  238807  .       -       2       Parent=Mnat_00001;
scaffold1       GeneWise        CDS     240781  240970  .       -       0       Parent=Mnat_00001;
scaffold1       GeneWise        CDS     241779  241912  .       -       2       Parent=Mnat_00001;
scaffold1       GeneWise        CDS     249825  250005  .       -       0       Parent=Mnat_00001;
scaffold1       GeneWise        CDS     273368  273452  .       -       1       Parent=Mnat_00001;
scaffold1       GeneWise        CDS     283460  283623  .       -       0       Parent=Mnat_00001;
scaffold1       Cuff    mRNA    316222  341723  1000    +       .       ID=Mnat_00002;evid_id=CCG000108.1;source_id=CUFF.1168.1;
scaffold1       Cuff    CDS     316222  316368  1000    +       0       Parent=Mnat_00002;
scaffold1       Cuff    CDS     322468  322630  1000    +       0       Parent=Mnat_00002;
scaffold1       Cuff    CDS     325120  325274  1000    +       2       Parent=Mnat_00002;
scaffold1       Cuff    CDS     329797  329922  1000    +       0       Parent=Mnat_00002;

I also have .bam files from RNAseq data which I would want to generate read counts from.

My code is as below:

for i in *sorted.bam; do
   htseq-count $i Mnat_gene_v1.2.gff -f bam -i -mRNA -t CDS -m union -r name --stranded=no > ${i}_count.txt;
done

However, the bash command does not seem to work. The error that I get is:

Error processing GFF file (line 2 of file Mnat_gene_v1.2.gff):
  Feature Mnat_00001 does not contain a 'mRNA' attribute
  [Exception type: ValueError, raised in features.py:387]

Has anyone come across such an error?