HI again @Ayushi_Bhagat ,
I would say that if this isn't working I would point you back to the issue that @Micro_Biologist pointed out.
Are you absolutely sure your sequencing has sufficient length to cover your target region with your trimming? See this post. What primers did you use? You might only have an overlap with no trimming because and as I mentioned
So, you can play with the --p-min-overlap setting in Dada2 to adjust this. i.e. try some tests with no trimming to see if this is the case somthing like:
qiime dada2 denoise-paired
--i-demultiplexed-seqs demux-paired-end-trimmed.qza
--p-trunc-len-f 0
--p-trunc-len-r 0
--p-min-overlap 10
--o-representative-sequences rep-seqs.qza
--o-table table.qza
--o-denoising-stats stats-dada2.qza
If that works then the issue is your sequence length vs your amplicon tagert length and you may need to proceed with forwrad reads only because your reverse reads will require trimming and that won't allow you to maintain the small overlap you had.