|Are there really spaces inside your strings?|
Did you mean:
mm/dd/yyyy to dd/mm/yyyy instead of mm / dd / yyyy to dd / mm / yyyy?
If so, what happened when you tried to reformat the dates?
If the spaces are really there, you won't be able to change it with formatting, you'll need a formula.
First, tell us if the spaces really belong there.
Click Here Before Posting Data or VBA Code ---> How To Post Data or Code.