User not showing in Spark

Hey everyone

First of all i use openfire and spark conversation systems in my business.First time i install everythings works good but 2-3 weeks later one of my user say to me no one seeing in my spark client.İt works fine 3 weeks after.İ thinks spark client is have problem and i uninstall client try again.Problem is not solved.Whatever i can't do anything this friend but 2 weeks later my client and 2 user client is not show anyone.İ add new user and i add spark user in client but not send request in client.

Please help me this problem.İm sorry my english not very good.But i think you understand my problem here is my log in openfire.

Error:

at org.apache.mina.core.filterchain.DefaultIoFilterChain.callNextMessageReceived(D efaultIoFilterChain.java:417)

at org.apache.mina.core.filterchain.DefaultIoFilterChain.access$1200(DefaultIoFilt erChain.java:47)

at org.apache.mina.core.filterchain.DefaultIoFilterChain$EntryImpl$1.messageReceiv ed(DefaultIoFilterChain.java:765)

at org.apache.mina.filter.codec.ProtocolCodecFilter$ProtocolDecoderOutputImpl.flus h(ProtocolCodecFilter.java:407)

at org.apache.mina.filter.codec.ProtocolCodecFilter.messageReceived(ProtocolCodecF ilter.java:236)

at org.apache.mina.core.filterchain.DefaultIoFilterChain.callNextMessageReceived(D efaultIoFilterChain.java:417)

at org.apache.mina.core.filterchain.DefaultIoFilterChain.access$1200(DefaultIoFilt erChain.java:47)

at org.apache.mina.core.filterchain.DefaultIoFilterChain$EntryImpl$1.messageReceiv ed(DefaultIoFilterChain.java:765)

at org.apache.mina.core.filterchain.IoFilterEvent.fire(IoFilterEvent.java:74)

at org.apache.mina.core.session.IoEvent.run(IoEvent.java:63)

at org.apache.mina.filter.executor.OrderedThreadPoolExecutor$Worker.runTask(Ordere dThreadPoolExecutor.java:769)

at org.apache.mina.filter.executor.OrderedThreadPoolExecutor$Worker.runTasks(Order edThreadPoolExecutor.java:761)

at org.apache.mina.filter.executor.OrderedThreadPoolExecutor$Worker.run(OrderedThr eadPoolExecutor.java:703)

at java.lang.Thread.run(Unknown Source)

2016.04.05 08:44:54 org.jivesoftware.openfire.handler.IQRosterHandler - Internal server error

java.lang.IllegalArgumentException: No enum constant org.xmpp.packet.Roster.Ask.subscr�be

at java.lang.Enum.valueOf(Unknown Source)

at org.xmpp.packet.Roster$Ask.valueOf(Roster.java:430)

at org.jivesoftware.openfire.roster.Roster.getAskStatus(Roster.java:579)

at org.jivesoftware.openfire.roster.Roster.getReset(Roster.java:547)

at org.jivesoftware.openfire.handler.IQRosterHandler.manageRoster(IQRosterHandler. java:189)

at org.jivesoftware.openfire.handler.IQRosterHandler.handleIQ(IQRosterHandler.java :122)

at org.jivesoftware.openfire.handler.IQHandler.process(IQHandler.java:66)

at org.jivesoftware.openfire.IQRouter.handle(IQRouter.java:372)

at org.jivesoftware.openfire.IQRouter.route(IQRouter.java:115)

at org.jivesoftware.openfire.spi.PacketRouterImpl.route(PacketRouterImpl.java:78)

at org.jivesoftware.openfire.net.StanzaHandler.processIQ(StanzaHandler.java:342)

at org.jivesoftware.openfire.net.ClientStanzaHandler.processIQ(ClientStanzaHandler .java:99)

at org.jivesoftware.openfire.net.StanzaHandler.process(StanzaHandler.java:307)

at org.jivesoftware.openfire.net.StanzaHandler.process(StanzaHandler.java:199)

at org.jivesoftware.openfire.nio.ConnectionHandler.messageReceived(ConnectionHandl er.java:181)

at org.apache.mina.core.filterchain.DefaultIoFilterChain$TailFilter.messageReceive d(DefaultIoFilterChain.java:690)

at org.apache.mina.core.filterchain.DefaultIoFilterChain.callNextMessageReceived(D efaultIoFilterChain.java:417)

at org.apache.mina.core.filterchain.DefaultIoFilterChain.access$1200(DefaultIoFilt erChain.java:47)

at org.apache.mina.core.filterchain.DefaultIoFilterChain$EntryImpl$1.messageReceiv ed(DefaultIoFilterChain.java:765)

at org.apache.mina.core.filterchain.IoFilterAdapter.messageReceived(IoFilterAdapte r.java:109)