Data source - Data set in Reports

Hi guys

I'm fooling around with some datasets in report builder.
First picture is showing "DataSet_result" which is standard. I have created Playlist and RadioShowLedger. Here I want to select only some of the datafields and I set condition on one of them as well.

My problem is that when I save the layout and then the report and runs it I get this error:

"A data source instance has not been supplied for the data source 'Playlist'."

If I have closed the report builder design view then the dataset is gone.

Is it not possible to create a dataset and use it?