Conversion error in checkboxgroup component.....

Question

hi
i have a checkboxgroup component. first time when i go this particular page no validation error occurs. but when i go to a different page and return back conversion error occurs in that component.
getSubmittedValue() method for that component returns some value when error occurs.
can anyone give some suggestions to resolve the error. or suggestions on the value to be converted for checkboxgroup

Answer 1

the actual code is
<cg:checkboxGroup binding="#{view$UsersSMSReport.action_chkbxgrp}" columns="1" id="action_chkbxgrp" style="width: 100%;"/>
<cg:message binding="#{view$UsersSMSReport.action_msg}" for="action_chkbxgrp" id="action_msg"/>
where cg is the our own tag discriptor file
we use jsp-api.jar and jstl.jar for customization of components.
the taglib file for this tag refers to class
CGCheckboxGroupTag extends UIComponentTag
the setProperties method in above class contains code for convertor
if(converter != null)
if(isValueReference(converter))
javax.faces.el.ValueBinding _vb = getFacesContext().getApplication().createValueBinding(converter);
component.setValueBinding("converter", vb);
} else
javax.faces.convert.Converter _converter = FacesContext.getCurrentInstance().getApplication().createConverter(converter);
component.getAttributes().put("converter", converter);
the design time class for this component is
CGCheckboxGroupBeanInfoBase extends SimpleBeanInfo
they are compiled into a tld file and added as complib file in project
the same component sometimes i get conversion error in validation phase and sometimes i get error in page displaying
java.lang.NullPointerException
ClassName:com.sun.rave.web.ui.util.ConversionUtilities
FileName ConversionUtilities.java
MethodName: convertValueToArray