1. Created a subsite and used the "Document Center" template.
2. Exported the "Upload a Document" button from that site.
3. Uploaded the button web part to the Web Part Library.
4. On the Home page I added the "Upload a Button" web part.
5. The button works on the subsite fine.
6. On the home page the button will not open the "upload.aspx" page.
Here is a copy of the code for the button. They are exactly the same for both the home page and subsite.