make_seq_mappoly by chromosome

[txuemei]

I am learning mappoly by watching "Tools for Polyploids Workshop: MAPpoly (01 14 2021)" (https://www.youtube.com/watch?v=NifLfBsQshQ). Video 30'16'': try to make sequence by using chr 10 markers, but doesn't work. Please let me know what I did wrong? Thanks for your help!

s10 <- make_seq_mappoly(dat, 'seq10')
s10
This is an object of class 'mappoly.sequence'
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Parameters not estimated
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Ploidy level: 4
No. individuals: 144
No. markers: 0

No. markers per sequence: not available
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No. of markers per dosage in both parents:

Error in strsplit(names(freq), "-") : non-character argument