Hi, DateList function expects it's argument to be a string. It looks like you are trying to pass a list of strings to it instead. To convert a list of strings you need to map over it (since DateList is not listable by default, probably because it has a list as second argument):
test = {"6/1/1990", "6/4/1990", "6/5/1990", "6/6/1990"} ;
Map[
DateList[{#,{"Day","Month","YearShort"}}]&,
test
]
You can always check whether a function is listable, i.e. f[{x1,x2,..}] = {f[x1],f[x2],...}, or not:
Attributes[Sin]
Attributes[DateList]
