ClassCastException and NullPointerException yet again

hi guys, i’ve modifed and recompiled webchat.war and it perfectly works on my windows openfire 3.9.3 server but when i tried to upload it on my debian openfire 3.9.3 server i encountered this error:

Our chat service is unavailable at this time. Please check back soon.
java.lang.ClassCastException: com.jivesoftware.smack.workgroup.ext.forms.WorkgroupForm cannot be cast to org.jivesoftware.smackx.workgroup.ext.forms.WorkgroupForm at org.jivesoftware.smackx.workgroup.user.Workgroup.getWorkgroupForm(Workgroup.jav a:842) at org.jivesoftware.webchat.actions.WorkgroupStatus.getWorkgroupForm(WorkgroupStat us.java:281) at org.jivesoftware.webclient.jsp.userinfo_jsp._jspService(userinfo_jsp.java:83) at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:97) at javax.servlet.http.HttpServlet.service(HttpServlet.java:820) …

i’ve tried what they did on (https://community.igniterealtime.org/thread/47634) spefically procedure 2 and yes it worked and continued on asking me thos name,email,etc information, but after clicking on the start chat button i got another error:

Our chat service is unavailable at this time. Please check back soon.
java.lang.NullPointerException at org.jivesoftware.webchat.actions.ChatStarter.startSession(ChatStarter.java:243) at org.jivesoftware.webclient.jsp.queue_jsp._jspService(queue_jsp.java:75) at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:97) at javax.servlet.http.HttpServlet.service(HttpServlet.java:820) at org.eclipse.jetty.servlet.ServletHolder.handle(ServletHolder.java:547) at …

and right now i’m stuck on figuring it out… i’ve tried building webchat.war on my debian but still got these errors … any ideas guys?