mySQL - Cannot add Foreign Key Constraint
I think you've got the FK the wrong way round, and really want:

ALTER TABLE  calltarget ADD 
CONSTRAINT `fk_importctbatch_calltarget_idImportCTBatch` 
FOREIGN KEY (`idImportCTBatch`) 
REFERENCES `importctbatch` (`idImportCTBatch`) 
ON DELETE RESTRICT;