[galaxy-user] Dataset does not appear in a drop-down menu of a tool

Hi, I just started using the main galaxy instance. I uploaded via FTP and imported several FASTQ files. They all appear in the list of my "saved datasets" (see attached screenshot). However, when I click on any of the tools in the left panel (e.g. "FASTQ Summary Statistics") I get in the middle panel the info for the tool but the dropdown menu listing the available FASTQ files is empty (see attached screenshot). What do I need to do to be able to perform analysis on the FASTQ files that I uploaded? many thanks, Nikolay