The screenshot is showing two errors
1) System.InvalidOperationException: Object is currently in use elsewhere
As per documentation, This error indicates a synchronization issue.
Close solution,
Close Visual Studio
Delete AUC files from the Business Connector user.
go to path where all visual studio development projects are located. Delete your Report from there
Restart reporting services, service
Open again the project from AOT and right click edit
now add data source
2) Field token value is invalid.
that means the specific field in not available in dataset or being used in wrong way. a very common example of this using a field in header or footer without specifying First in expression. Since fields in header and footer do not belong to any dataset of tablix of body. so it is must to specify First and DataSetName, so it can take value in right context