[Problems]Hazelcast plugin along with other custom plugins

I use openfire 3.8.1 and hazelcase plugin 1.0.4.

I created a customized plugin(let's call it myPlugin.jar). Before I apply hazelcast.jar, everything runs perfectly. Because my business has scale requirement, I start to research hazelcast plugin. The problem is, when I deployed both myPlugin.jar and hazelcast.jar and start the openfire, the console log doesn't show the cluster plugin startted properly. But if I remove myPlugin.jar, I can see from the log that the cluster plugin start correctly.

I tried other plugins (built from openfire source) along with hazelcast and works well. Seems it complains only to my plugin. What's the possible reason? What can I do to debug this issue?