Alter table adding Foreign SQLlite android

im working with databases in android and y need make upgrade on a table adding a Foreign key:

> ALTER TABLE equipo  ADD FOREIGN KEY (tipo) REFERENCES CUSTOMER
> (examen);

But the SQLite show this error:

SQLiteManager: Likely SQL syntax error: ALTER TABLE equipo ADD FOREIGN KEY (tipo) REFERENCES CUSTOMER (examen); [ near "FOREIGN": syntax error ] Exception Name: NS_ERROR_FAILURE Exception Message: Component returned failure code: 0x80004005 (NS_ERROR_FAILURE) [mozIStorageConnection.createStatement]