Custom Report Error

I've been using the Custom Report feature today. I have one custom field that I added to the Request screen. Each time I use the custom field as one of the filters I receive the error below.

[begin error message]
HTTP Status 500 -

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type Exception report

message

description The server encountered an internal error () that prevented it from fulfilling this request.

exception

javax.servlet.ServletException: [B
org.apache.struts.action.RequestProcessor.processException(RequestProcessor.java:545)
org.apache.struts.action.RequestProcessor.processActionPerform(RequestProcessor.java:486)
org.apache.struts.action.RequestProcessor.process(RequestProcessor.java:274)
org.apache.struts.action.ActionServlet.process(ActionServlet.java:1482)
org.apache.struts.action.ActionServlet.doPost(ActionServlet.java:525)
javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
javax.servlet.http.HttpServlet.service(HttpServlet.java:810)
com.adventnet.servicedesk.filter.EncodingFilter.doFilter(EncodingFilter.java:72)
com.adventnet.authentication.ContextChangeDetector.doFilter(ContextChangeDetector.java:100)
org.jboss.web.tomcat.filters.ReplyHeaderFilter.doFilter(ReplyHeaderFilter.java:75)

root cause

java.lang.ClassCastException: [B
com.adventnet.servicedesk.helpdesk.reports.utils.CustomReportUtil.getComputedValues(CustomReportUtil.java:677)
com.adventnet.servicedesk.reports.helpdesk.action.CustomReportAction.execute(CustomReportAction.java:213)
org.apache.struts.action.RequestProcessor.processActionPerform(RequestProcessor.java:484)
org.apache.struts.action.RequestProcessor.process(RequestProcessor.java:274)
org.apache.struts.action.ActionServlet.process(ActionServlet.java:1482)
org.apache.struts.action.ActionServlet.doPost(ActionServlet.java:525)
javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
javax.servlet.http.HttpServlet.service(HttpServlet.java:810)
com.adventnet.servicedesk.filter.EncodingFilter.doFilter(EncodingFilter.java:72)
com.adventnet.authentication.ContextChangeDetector.doFilter(ContextChangeDetector.java:100)
org.jboss.web.tomcat.filters.ReplyHeaderFilter.doFilter(ReplyHeaderFilter.java:75)

note The full stack trace of the root cause is available in the Apache Tomcat/5.0.28 logs.

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Apache Tomcat/5.0.28
[end error message]

Will we not be able to use custom fields as filters in custom reports?

Thanks
David