Database fail over in weblogic5.1 cluster environment

[venki janapati]

Hi,
I am using weblogic5.1 clustered environment with two databases one is master& other one is slave.I need to switch over to other database if one fails.I implemented this logic in my code by making statement & if it fails then switch over to different connection pool.This works well in single weblogic instance(without cluster) & it is not working properly in clustered environment(some times switch over & some times not).If some one knows the problems related to clustered environment, pls let me know.
Thanks in advance.
Venki