I tore my hair out for several days over this one!
After converting web site and reports from VS2008 to VS2010, some (not all) of my reports stopped working.
All I would see was "one or more datasources is missing credentials"
I used a bare bones reportviewer control on my aps.net page, and programmatically connected it to the report and to the dataset.
This worked just fine in vs2008.
It turns out I needed a more fleshed out default report viewer .... one with the local report and a datasource specified..... even though I would replace them later in my code behind.
After converting web site and reports from VS2008 to VS2010, some (not all) of my reports stopped working.
All I would see was "one or more datasources is missing credentials"
I used a bare bones reportviewer control on my aps.net page, and programmatically connected it to the report and to the dataset.
This worked just fine in vs2008.
It turns out I needed a more fleshed out default report viewer .... one with the local report and a datasource specified..... even though I would replace them later in my code behind.