How do I bind radio buttons to a single field.

Here's what I've tried

I have a Bizobj called "boTest" with a character field "cData"
Dropped an mmPanel onto a form
Dropped an mmRadioButton named "optOne" onto the panel
Dropped an mmRadioButton named "optTwo" onto the panel
I set the BindingProperty of optOne and optTwo to "Tag"
I set the BindingSource of optOne, and optTwo to boTest
I set the BindingSourceMember of optOne, and optTwo to cData
I set the Tag of optOne to "one"
I set the Tag of optTwo to "two"

In the record I'm viewing, I've set the cData field to "two"

No errors are raised, and neither of the mmRadioButtons are checked

Any suggestions?

Do I drop them on an mmGroupBox and set the binding properties of the mmGroupBox rather than the mmRadioButtons?

Thanks,
Rick