I think that since the table existed as listed in the first error the constraint was not imported, therfore it can not be enabled.

Maybe this would work, i'm not sure.
constraints=y
ignore=y


In situations where multiple refreshes from a single export file are done with IGNORE=Y, certain objects can be created multiple times (although they will have unique system-defined names). You can prevent this for certain objects (for example, constraints) by doing an import with the value of the parameter CONSTRAINTS set to N. If you do a full import with the CONSTRAINTS parameter set to N, no constraints for any tables are imported.


MH