Unnecessary Locks -- Help!

We have experienced locking problems from a new program we developed. We subsequently developed the following test cases. All test cases are using the same table A with key -- char(11), col -- char(2), and all sqls are using repeatable read. case 1: from one telnet session: insert into A (key, col) values ("A00000B0001", null); row inserted from another telnet session: insert into A (key, col) values ("A00000B0002", null); key value lock case 2: from one telnet session: insert into A (key, col) values ("A00000B0001", null); row inserted from another telnet session: insert into A (key, col) values ("A00001B0001", null); row inserted So, OnLine works as it should be. But here comes the problem. We defined a foreign key from col of table A to table B. Now even test case 2 got key value lock regardless whatever values col is using. Can anyone explain it? Is it because repeatable read locks the referenced table? Is there a way to avoid the locking yet still maintain repeatable read? Chao