Symptoms
When you connect to SQL Server using the SQL Server OLE DB Provider, if you use ActiveX Data Objects Extensions for DDL and Security (ADOX), the ADOX Column object exposes six dynamic properties in its Properties collection: Autoincrement, Default, Fixed Length, Nullable, Primary Key, and Unique.
However, any attempt to read one of these properties on an existing Column in an existing Table generates the following error message:

Error 3251, “Object or provider is not capable…” You may also encounter problems when you try to set these properties on a new Column unless you follow specific steps, which are described in the “More Information” section.
Resolution
Because you cannot use ADOX to read these Column properties, you can use an ADO Connection or SQL Server Query Analyzer to run the equivalent T-SQL statements to query object properties; or you can use SQL Server Enterprise Manager to view the properties manually.