ERROR: No variation in sampling dates! Please specify your clock rate explicitly

[BCMollett]

Hi,

I am running treetime with treetime --covariation --confidence --clock-filter 5 --tree <input.nwk> --aln <input.aln.fasta> --dates <input.csv>' on a selection of N1 subtype influenza viruses and it is returning the following:

ValueError: No variation in sampling dates! Please specify your clock rate explicitly.

ERROR: No variation in sampling dates! Please specify your clock rate explicitly.

ERROR in TreeTime.run: An error occurred which was not properly handled in TreeTime. If this error persists, please let us know by filing a new issue including the original command and the error above at: https://github.com/neherlab/treetime/issues

The dataset contains sequences with dates from 2014-2021 and I have previously used the same command for N2 subtype and all other gene segments without error. I am sure all headers and dates are correct/matching

Do you have any idea/advice on how to get around this issue?

Thanks, Ben