Java1.5 with ATG6.4

Trying to run ATG6.4.0 on the below java version

Dynamo 6.3.0 p3

java version "1.5.0_15"

Java(TM) 2 Runtime Environment, Standard Edition (build 1.5.0_15-b04)

Java HotSpot(TM) Server VM (build 1.5.0_15-b04, mixed mode)

java full version "1.5.0_15-b04"

Getting the below error while accesing the index page when trying to login..

Error getting compiled page
javac: target release 1.3 conflicts with default source release 1.5

Could you please let me know about resolving this issue.

Thanks in Advance

JP