Error Code: 1215. Cannot add foreign key constraint new

this is the query I am using :

alter table publication1 add foreign key (Venuekey) references publicationvenue.venueKey

and the following are the two tables of this query:

Publication Table:

CREATE TABLE `publication1` 
(

 `keypub` varchar(200) CHARACTER SET latin1 COLLATE latin1_general_cs NOT NULL,

 `title` varchar(700) DEFAULT NULL,

 `booktitle` varchar(250) DEFAULT NULL,

 `journal` varchar(250) DEFAULT NULL,

 `volume` varchar(50) CHARACTER SET latin1 DEFAULT NULL,

 `month` varchar(50) CHARACTER SET latin1 DEFAULT NULL,

  `year` varchar(50) CHARACTER SET latin1 DEFAULT NULL,

  `cdrom` varchar(250) CHARACTER SET latin1 DEFAULT NULL,

  `ee` varchar(500) CHARACTER SET latin1 DEFAULT NULL,

  `publisher` varchar(250) CHARACTER SET latin1 DEFAULT NULL,

  `pages` varchar(50) CHARACTER SET latin1 DEFAULT NULL,

  `number` varchar(50) CHARACTER SET latin1 DEFAULT NULL,

  `url` varchar(500) CHARACTER SET latin1 DEFAULT NULL,

  `cite` varchar(250) CHARACTER SET latin1 DEFAULT NULL,

  `address` varchar(250) CHARACTER SET latin1 DEFAULT NULL,

  `note` varchar(500) CHARACTER SET latin1 DEFAULT NULL,

  `isbn` varchar(50) CHARACTER SET latin1 DEFAULT NULL,

  `series` varchar(250) CHARACTER SET latin1 DEFAULT NULL,

  `school` varchar(250) CHARACTER SET latin1 DEFAULT NULL,

  `chapter` varchar(250) CHARACTER SET latin1 DEFAULT NULL,

  `crossref` varchar(250) CHARACTER SET latin1 DEFAULT NULL,

  `type` varchar(30) CHARACTER SET latin1 DEFAULT NULL,

  `venueClean` varchar(250) DEFAULT NULL,

  `venuekey` varchar(200) DEFAULT NULL,

  PRIMARY KEY (`keypub`),

  KEY `venue_index` (`venueClean`)

  ) ENGINE=InnoDB DEFAULT CHARSET=utf8 COMMENT='InnoDB free: 49152 kB;  

  InnoDB free: 5424128 kB';

And the second table is PublicationVenue:

  CREATE TABLE `publicationvenue` (

  `venuekey` varchar(200) NOT NULL,

  `VenueName` varchar(1000) DEFAULT NULL,

  PRIMARY KEY (`venuekey`)

  ) ENGINE=InnoDB DEFAULT CHARSET=utf8;

I have set the default charset same for both tables and columns and done all sort of thing but still cant resolve this query please help?