What do you mean by "it won't enter"? typically outside where you name your "animal" followers nothing changes, however despite no confirmation of name change or visual change outside, in the Animals tab the name should have been applied
When you type in the name and press enter did you then check the animals tab ( it's in the same place as the prison and workbench tabs, it's the button with a tools symbol on it) to see if it actually applied to your raptor? Because as I said, where you name the "animals" there is no indication that you did anything, it just sets the name and throws you back a few menu's