filtering dates

I am trying to filter data to just see dates before 2018-02-01

dplyr::filter(dataframe, dataframe$DATE<'2018-02-01')

With this command, I am still getting the February data in my outcome. Any ideas why?

Thanks in advance

edit: I know I could just do a <= '2018-01-31' but odd that my first thought isn't working

A reproducible example would be useful: