Hi,
I'm using the latest version of your product (7.2).
I've been searching through the documentation for 2 days now and trying demystify the art around trying to force an end user to only make one selection on the AspxGridView control, as opposed to the default multi-row selection behaviour.
I've tried using the client-side events, but this is somewhat tricky:
I've hooked the RowClick ClientSide event to a JScript function as follows:
function(s, e) {
s.UnselectRows();
s.SelectRows(e.visibleIndex);
}
The first line works fine, the second line throws a "Missing Primary Key Exception".
To mitigate this, I've also set the KeyFieldName in both design time and also at run time.
Even through all of this, I still can't seem to get this to work! 
Please shed some wisdom on this subject?
I've looked into the sample on the site regarding using Radio Buttons, but I don't want to make an unnecessary call to the server just because the user selected a row...
When I use s.SelectRow(e.visibleIndex, true); I don't get an error, but it doesn't physically select the row either??? It just focuses the row...
My code to bind the grid to a datasource is as follows:
agvProperties.KeyFieldName =
"PropertyID";
agvProperties.DataSource = props;
agvProperties.DataBind();