java.lang.IllegalArgumentException: Width (0) and height (0) cannot be <= 0

In my RTC server's ccm.log,this error appear:

2013-05-27 20:02:14,458 [        http-bio-9443-exec-110] ERROR com.ibm.team.rtc.common.service                     - Problems serving sprite image service request
java.lang.IllegalArgumentException: Width (0) and height (0) cannot be <= 0
 at java.awt.image.DirectColorModel.createCompatibleWritableRaster(DirectColorModel.java:1010)
 at java.awt.image.BufferedImage.<init>(BufferedImage.java:332)
 at com.ibm.team.rtc.common.internal.service.web.sprite.layout.SpriteImageCreator.process(SpriteImageCreator.java:80)
 at com.ibm.team.rtc.common.internal.service.web.sprite.SpriteBuilder.buildSprite(SpriteBuilder.java:123)
 at com.ibm.team.rtc.common.internal.service.web.sprite.SpriteImageService.buildFromProcessArea(SpriteImageService.java:277)
 at com.ibm.team.rtc.common.internal.service.web.sprite.SpriteImageService.serveProcessAttachmentRequest(SpriteImageService.java:136)
 at com.ibm.team.rtc.common.internal.service.web.sprite.SpriteImageService.perform_GET(SpriteImageService.java:99)
 at com.ibm.team.repository.service.TeamRawService.service(TeamRawService.java:82)
 at sun.reflect.GeneratedMethodAccessor506.invoke(Unknown Source)
 at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:37)
 at java.lang.reflect.Method.invoke(Method.java:611)
 at org.eclipse.soda.sat.core.internal.record.ExportProxyServiceRecord.invoke(ExportProxyServiceRecord.java:361)
 at org.eclipse.soda.sat.core.internal.record.ExportProxyServiceRecord.access$0(ExportProxyServiceRecord.java:347)
 at org.eclipse.soda.sat.core.internal.record.ExportProxyServiceRecord$ExportedServiceInvocationHandler.invoke(ExportProxyServiceRecord.java:56)
 at $Proxy1950.service(Unknown Source)
 at com.ibm.team.repository.servlet.AbstractTeamServerServlet.doRestService(AbstractTeamServerServlet.java:914)
 at com.ibm.team.repository.servlet.AbstractTeamServerServlet.handleRequest2(AbstractTeamServerServlet.java:2100)
 at com.ibm.team.repository.servlet.AbstractTeamServerServlet.handleRequest(AbstractTeamServerServlet.java:1924)
 at com.ibm.team.repository.servlet.AbstractTeamServerServlet.service(AbstractTeamServerServlet.java:1800)
 at javax.servlet.http.HttpServlet.service(HttpServlet.java:722)
 at org.eclipse.equinox.http.registry.internal.ServletManager$ServletWrapper.service(ServletManager.java:180)
 at org.eclipse.equinox.http.servlet.internal.ServletRegistration.service(ServletRegistration.java:61)
 at org.eclipse.equinox.http.servlet.internal.ProxyServlet.processAlias(ProxyServlet.java:126)
 at org.eclipse.equinox.http.servlet.internal.ProxyServlet.service(ProxyServlet.java:76)
 at javax.servlet.http.HttpServlet.service(HttpServlet.java:722)
 at org.eclipse.equinox.servletbridge.BridgeServlet.service(BridgeServlet.java:120)
 at com.ibm.team.repository.server.servletbridge.JazzServlet.service(JazzServlet.java:68)
 at javax.servlet.http.HttpServlet.service(HttpServlet.java:722)
 at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:305)
 at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
 at com.ibm.team.repository.server.servletbridge.BridgeFilter.processDelegate(BridgeFilter.java:133)
 at com.ibm.team.repository.server.servletbridge.BridgeFilter.doFilter(BridgeFilter.java:154)
 at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:243)
 at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
 at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:222)
 at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:123)
 at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:581)
 at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:168)
 at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:99)
 at org.apache.catalina.authenticator.SingleSignOn.invoke(SingleSignOn.java:336)
 at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:118)
 at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:407)
 at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1002)
 at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:585)
 at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:310)
 at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:897)
 at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:919)
 at java.lang.Thread.run(Thread.java:738)

why appear this error?