Picard, extracting unmapped reads and converting it to FASTQ

[gabrieledcjr]

I'm currently using Picard to extract unmapped reads from a BAM file which has been successfully done. However, I'm trying to convert it back to FASTQ still using Picard. But the output is blank. I'm not even sure if this is possible. Any help would be much appreciated!

I only need to work with the unmapped reads of the BAM file but I need it converted to FASTQ file.