**This bug has been fixed at ArcGIS 9.3.**The Dissolve tool returns incorrect results when the dissolve field is text, and contains uppercase and lowercase values.
This is a known issue in ArcGIS 9.0, 9.1, and 9.2 releases.
If the values of the field do not need to be uppercase and lowercase, edit the field values to make the case of the values consistent.
If the case needs to be upper and lower, follow the steps below to perform a Summarize on the dissolve field of the original dataset.
- Add a new field.
- Define the field as a Short or Long Integer and name the field DissolveB.
- Join the origin dataset to the destination dataset, based on the original dissolve field, DissolveA.
- Calculate the origin.DissolveB field to be equal to destination.OID.
- Remove the Join.
- Run the dissolve based on the DissolveB field.