You did an OOPSIE...
You have a text box named ProjectNameBox. I don't see a control named ProjectCodeBox, so I'll bet that is the issue.
In regards to finding the error, press the Debug button instead of quitting. Then slowly press F8 until you get to where the missing object becomes apparent.
To avoid the error in the first place, when typing the control names in, qualify (preface) them with the Me keyword and a stop (period). You will see that upon typing the stop, all of the userform's properties are displayed, including your controls. Makes it a lot harder to misspell or refer to a non-existent control
Hope that helps,
Mark