Captcha

Hi everybody, im programming on java with redhat 5.0 server and jboss as a webserver.

I have a this error:

Code:

17:54:10,102 ERROR [[Captcha]] Servlet.service() for servlet Captcha threw exception

java.awt.HeadlessException

       at sun.java2d.HeadlessGraphicsEnvironment.getDefaultScreenDevice(HeadlessGraphicsEnvironment.java:64)

       at ni.com.xolo.captcha.text.imp.DefaultWordRenderer.renderWord(DefaultWordRenderer.java:46)

       at ni.com.xolo.captcha.servlet.DefaultCaptchaIml.createImage(DefaultCaptchaIml.java:90)

       at ni.com.xolo.captcha.servlet.CaptchaServlet.doGet(CaptchaServlet.java:38)

       at javax.servlet.http.HttpServlet.service(HttpServlet.java:690)

       at javax.servlet.http.HttpServlet.service(HttpServlet.java:803)

       at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290)

       at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)

       at org.jboss.web.tomcat.filters.ReplyHeaderFilter.doFilter(ReplyHeaderFilter.java:96)

       at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)

       at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)

       at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:230)

       at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:175)

       at org.jboss.web.tomcat.security.SecurityAssociationValve.invoke(SecurityAssociationValve.java:179)

       at org.jboss.web.tomcat.security.JaccContextValve.invoke(JaccContextValve.java:84)

       at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:127)

       at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102)

       at org.jboss.web.tomcat.service.jca.CachedConnectionValve.invoke(CachedConnectionValve.java:157)

       at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)

       at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:262)

       at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:844)

       at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:583)

       at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:446)

       at java.lang.Thread.run(Thread.java:619)

when i try to see the page that renders the captcha. do you know something can help me?