The DataForm consists of two major objects: Fields and Tabs.  Tabs can contain Fields, or Fields can float free in the DataForm.  If you chose to use Tabs, they will not appear in the DataForm using the default DataForm template.  To see Tabs you must be using the Tab Form template for the DataForm.  But using the Tab Form Template will make any Fields free floating in the DataForm disappear.

The solution is to create the DataForm, Tabs and Fields in a specific order.   

1. Create the Data Form, but do not create any fields.
2. Change the Data Form Template to "Tab Form".
3. Exit the Data Form wizard without creating any fields.
4. Select the "Add a Tab" from the Data Form header.
5. After creating all the Tab(s) you need, select "Add a field" from the Data Form header.
6. While creatingFields in the wizard, you must assign the field to a tab, or it will not be visible under the Tab Form template.
7. Keep adding tabs and fields in this order until you are finished.

Should you find that you forget to assign a field to a tab then do not despair. Simply edit the data form and change the data form template to be 'Default DataForm' rather than 'Tab Form'. When you return to the form you will be missing all your tabs but you will have those fields that were not assigned to a tab. Once you have all the fields assigned to tabs you can switch the data form template back to 'Tab Form'