Java Error at SSHRA

Hi,

i faced issue on one of Self service requests (SIT) ' Petty cash ' when i fill it and reach to submit page click on the submit button its not going to next page (no response) and you need click again .. after second clicking we face the below java error !

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Error Page 
Exception Details. 
 oracle.apps.fnd.framework.OAException: java.lang.NumberFormatException: null
        at oracle.apps.fnd.framework.OAException.wrapperException(OAException.java:912)
        at oracle.apps.per.selfservice.workflowservice.server.WFUtility.getActivityId(WFUtility.java:1760)
        at oracle.apps.per.selfservice.workflowservice.server.WFUtility.getActivityId(WFUtility.java:1718)
        at oracle.apps.per.selfservice.review.webui.ReviewCO.processFormRequest(ReviewCO.java:414)
        at oracle.apps.fnd.framework.webui.OAWebBeanHelper.processFormRequest(OAWebBeanHelper.java:819)
        at oracle.apps.fnd.framework.webui.OAWebBeanContainerHelper.processFormRequest(OAWebBeanContainerHelper.java:385)
        at oracle.apps.fnd.framework.webui.OAPageLayoutHelper.processFormRequest(OAPageLayoutHelper.java:1205)
        at oracle.apps.fnd.framework.webui.beans.layout.OAPageLayoutBean.processFormRequest(OAPageLayoutBean.java:1579)
        at oracle.apps.fnd.framework.webui.OAWebBeanHelper.processFormRequestChildren(OAWebBeanHelper.java:1031)
        at oracle.apps.fnd.framework.webui.OAWebBeanHelper.processFormRequestChildren(OAWebBeanHelper.java:997)