[rsMissingDataSetName] The data set name is missing in the data region ‘DataSetName’

It is a very common compilation error that Visual studio throws when you try to add multiple datasets to your report (.rdl) file. At the time of this writing, i am using MS Visual studio 2008 and developing a report to be deployed on SQL Server 2005 database. I had the following two datasets :
1. dataset1: To retrieve the stored procedure and fill the table in the report with the data
2. dataset2: The stored procedure requires two input parameters (one is date and other is list of valid values) To populate the list of valid values, i need to get the data from database. I used this dataset to query the table and return the list of valid values.

Here is how you can fix this compilation problem:
1. Open the layout tab of your report.
2. Select the table where dataset1 is being used.
3. Right-click and select the "properties" menu option. You should be able to see the table properties on right hand side lower pane.
4.  Under the table properties, look for DataSetName. You should see the drop down with two datasets you defined i.e.e dataset1 and dataset2. Select the dataset1 and save it.
5. Recompile and the compilation error should be gone by now.

Hope this helps.

Thanks.!!!