InfoPath Dev

I have created an infopath form template and deployed it to a web server. It submits data to a web service. However, when I open an existing form from the web, the check boxes are all disabled. Text boxes are not disabled. Any ideas why this could be?

Here's an overview of how it works:
-User opens form, fills it out (checkboxes appear fine)
-User submits form to webservice
-Webservice stores form data
-Web page lists forms
-User clicks a form
-ASP.NET page sends form XML to browser, with processing instructions, etc.
-Populated form appears in InfoPath, EXCEPT checkboxes are now disabled!

More digging revealed this was due to the checkboxes being defined using nillable=true, which causes xsd.exe to generate classes that rely on Nullable<boolean>, which xsd.exe implements poorly. So, now my question is:

Is it possible to make those fields nillable=false using only the InfoPath designer? Making them required doesn't do it. I read the article on optional vs requried here, and it shows how to edit it in the xsd, but I was really hoping to rely on InfoPath to design the xsd.

I doubt you can do it within the InfoPath designer, but would love to be proved wrong.

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Matt Faus
InfoPath Dev Texas