LINQ and FormView

[Ben]

I'm having difficulty connecting a FormView to a LINQ to SQL query for
updating. I think this should be easy, but I've hit a dead end.

I'm trying to drive a FormView with a LinqDataSource, allowing for the
editing of a particular record. I've used the designer to build a
LinqDataSource, and put it on my web page. I've added a FormView, told it
to use the LinqDataSource as the Data Source, and I kick it into Edit mode.
The data for the record displays perfectly. When I click the Update link in
the FormView, I get this message:
LinqDataSource 'ldsGetRecording' does not support the Update operation
unless EnableUpdate is true.

Ok, no problem. I set the Enablex proprty to true (I've tried this both by
setting it via the property window, and by reconfiguring the datasource:
clicking the Advanced button, and checking the box to automatically process
updates). Now when I click the Update link in the FormView, I get this
message:
LinqDataSource 'ldsGetRecording' does not support the Select property when
the Delete, Insert or Update operations are enabled.

So, I can select but not update, or update but not select. That can't be
right. What am I missing?
Thanks.