I'm trying to extract the unmapped reads that appear in the "*" region when samtools idxstats is run. However, when I run samtools view -b [filename] '*' and then convert to a fastq using samtools bam2fq, the resulting fastq file is empty, and I get the message that 0 reads were processed. However, samtools idxstats definitely shows that there were unmapped reads under "*". Did I extract the reads incorrectly? If not, what else could be the problem? Thanks in advance!