jsf 1.2 - JSF Identify errors generated in process validations phase -

i'm new jsf , want make modifications in existing code. while code working fine, have problem a4j (rich faces) onchange event.

my tech stack related here jsf1.2, richfaces 3.3

the code snippet below:

<h:selectonemenu required="#{order.required}"                  id="modelcbfs" label="model" value="#{order.modeldto}" converter="modelconverter">     <f:selectitem itemlabel="-select-" itemvalue =""/>     <f:selectitems value="#{order.modeldropdown}" />     <a:support ajaxsingle="false" limittolist="true"                rerender="elevationcbfs"                event="onchange"                action="#{order.modelchanged}"                onsubmit="onhourglass()" oncomplete="offhourglass()"/> </h:selectonemenu> 

now, when above code rendered on page, ajax event being fired, jsf page not go thru 4th , 5th phases (update values , invoke application phases) first onchange event! works correctly subsequent requests though. also, onchange a4j events every other component works fine.

when researched on net, solution debug issue use facescontext , use debug messages it. not configured in current app.

can me solution debugging issue? or possible root causes appreciated.

i found out problem! enabling , disabling fields based on master method in rule conflicting in child particular field..

nevertheless absurd on way approached problem trial , error method...

if have thoughts on have happened technically, please shed light!