I am having difficulty using Concatenate. When I try to concatenate fastq.gz datasets corresponding to different flow cells (datasets 1 to 4), the ~200 MB datasets are concatenated into an ~2 KB fqtoc file, instead of a larger (I'd guess ~800 MB?) fastq.gz file. Consequently, the concatenated file (which doesn't appear to be concatenated at all) cannot be used, for example, in fastqc (which of course requires at least that a fastq.gz file be the input). Any help would be greatly appreciated.