I found the answer just now, with having spent about 5hrs on it. After having an hour break, came back to it and what it is, is I've RatePerHourTextBox.Text = HrlyRate

As it reads that from right to left and doesn't have a value beforehand it becomes nothing. So when I then read it in the other form as ManageUsers.HrlyRate there's obviously nothing in the variable.

Yup, you've probably guessed it if you're reading this - switch the two around to HrlyRate = RatePerHourTextBox.Text and it's problem solved :|

Sometimes I really hate programming....