Help: MySQL foreign key error

[Djeunut]

I'm trying to make a foreign key but MySQL keeps telling me there is a duplicate key and I have no clue why or where there is a duplicate.

Operation failed: There was an error while applying the SQL script to the database.
Executing:
ALTER TABLE `stemmy`.`stemmen` 
ADD CONSTRAINT `idPartij`
  FOREIGN KEY (`idPartij`)
  REFERENCES `stemmy`.`partijen` (`idPartij`)
  ON DELETE NO ACTION
  ON UPDATE NO ACTION;

ERROR 1005: Can't create table `stemmy`.`stemmen` (errno: 121 "Duplicate key on write or update")
SQL Statement:
ALTER TABLE `stemmy`.`stemmen` 
ADD CONSTRAINT `idPartij`
  FOREIGN KEY (`idPartij`)
  REFERENCES `stemmy`.`partijen` (`idPartij`)
  ON DELETE NO ACTION
  ON UPDATE NO ACTION

 

[Djeunut]

We found the issue, there was a problem with the naming since it can't have the same name as another foreign key and the table had to be empty for some reason.