Error: Failed to enable constraints. One or more rows contain values violating non-null, unique, or foreign-key constraints.

Possible Solution:

Review every field in the DataTable that feeds the report.

Ensure that all fields that could possibly be NULL allow nulls.

This means, but is not limited to, any fields that are identified as Primary keys and Integers.  (Delete Primary Keys)

Also, ensure that all String datatypes have a NullValue property setting of (Empty) instead of (Throw exception)

Right-click -> Configure… -> Finish -> Build

If that doesn’t clear the error, delete the dataset and re-create it (make sure you keep the same name.)

If that doesn’t clear the error, then the report probably has a problem getting any data at all (and no data = null.  Thanks Microsoft engineers.)

For a *really*painful* way out of this problem, see SJHCWorkplace.aspx.cs.