"not s4" error with get_fastq()

[francoiskroll]

Probably not an actual issue with the package, but I am not sure where to ask. I am having a little difficulty with the get_fastq() command. I am using data I found online as a test (chr20:part5, https://github.com/nanopore-wgs-consortium/NA12878/blob/master/Genome.md).

get_fastq(.../DEAMERNANOPORE_20161117_FNFAB43577_MN16450_sequencing_run_MA_821_R9_4_NA12878_11_17_16_88738_ch66_read1033_strand1.fast5)

Warning message:
In get_fastq(".../DEAMERNANOPORE_20161117_FNFAB43577_MN16450_sequencing_run_MA_821_R9_4_NA12878_11_17_16_88738_ch66_read1033_strand1.fast5") :
  not s4

Can you help?