Canonical Date-2 date fields from the same table

[antupe]

I have read several posts about canonical date, but I am still not getting it right. I have two different date fields (FechaEntradaTODO and HoraAceptadoTODO) within the same table and I need a canonical date in order to represent these in the same graph.

This is my script:

For most of the dates it is working correctly but for some reason some are not working, like the following, where two dates that have nothing to do with one another  appear as CanonicalDate:

Any idea  of why this is happening, maybe I am not mapping correctly? Or could it be because both variables come from the same table?