A foreign key constraint fails

Hello Forum,

currently i'm working on a MySQL Database.

For visualize the database, i set some foreign keys inside. In most cases it works perfectly, but in two cases not.

I tried:

ALTER TABLE tbl_uebergabe_details
ADD CONSTRAINT tbl_uebergabe_details_tbl_uebergabe_ID_fk
FOREIGN KEY (UebergabeID) REFERENCES tbl_uebergabe (ID);

but i got:

[23000][1452] (conn=604) Cannot add or update a child row: a foreign key constraint fails (`hilland`.`#sql-d14_25c`, CONSTRAINT `tbl_uebergabe_details_tbl_uebergabe_ID_fk` FOREIGN KEY (`UebergabeID`) REFERENCES `tbl_uebergabe` (`ID`))

Does anyone knows more about this error?

Greetings

Sascha