What I said about hating ObjectDataSource doesn’t count. SQLDataSource is worse. At least ObjectDataSource gives you error messages when it isn’t working. SQLDataSource appears not to work at all with stored procedures that have parameters. I found this forum thread that seemed to describe my problem. Unfortunately, none of the tactics suggested worked for me. I don’t even get error messages, just a screen with no GridView control in it. One of my colleagues looked at it and was just as stumped as I am.
Using an XSD, a couple lines of code, and an ObjectDataSource got me the result I needed with far less hassle.