Data Entry

I am trying to create a foolproof Excel time card for employees to enter their time. Employees must be able to choose a client from one drop down list, a project from the next (which is dependent on the client chosen), and a task from the last (which is dependent on the project chosen). I have got this far, but if the title of the client or project contains multiple words or other characters, I cannot get it to work. I know this is possible for someone who knows how to do it. Ideally you can teach me how it's done so I can customize further.