form jsf 2.0 issue

a4j:commandButton not calling my action in first time but after the first click it works perfectly.

This problem happened to me every reloading of the page.

Below is some part of my code

<form id="NClient">
    <table>
        <tr>
            <td><rich:panel id="panelClient">
                    <f:facet name="header">
                        <h:panelGroup>
                            <h:outputText value="#{i18n.LABEL_NOUV_CLIENT}"></h:outputText>
                        </h:panelGroup>
                    </f:facet>
                    <div>
                        <table>
                            <a4j:outputPanel ajaxRendered="true">
                                <b><h:messages
                                        id="msgs"
                                        style="color: red;font-size: 12px;font-style: oblique;font-style: italic;" /></b>
                            </a4j:outputPanel>
                            <tr>
                                <td><b><h:outputText value="Raison Sociale* : " /></b></td>
                                <td><h:inputText
                                        id="rs"
                                        required="true"
                                        requiredMessage="Veuillez remplir le champ requis Raison sociale"
                                        value="#{ClientBean.currentClt.rs}" /></td>
                            </tr>
                            <tr>
                                <td><b><h:outputText value="email* : " /></b></td>
                                <td><h:inputText
                                        id="email"
                                        required="true"
                                        requiredMessage="Veuillez remplir le champ requis Email"
                                        value="#{ClientBean.currentClt.email}" /></td>
                            </tr>
                            <tr>
                                <td><b><h:outputText value="Adresse* : " /></b></td>
                                <td><h:inputTextarea
                                        value="#{ClientBean.currentClt.adresse}"
                                        id="adresse"
                                        required="true"
                                        requiredMessage="Veuillez remplir le champ requis adresse " /></td>
                            </tr>
                            <tr>
                                <td><b><h:outputText value="Ville* : " /></b></td>
                                <td><h:inputText
                                        value="#{ClientBean.currentClt.ville}"
                                        id="ville"
                                        required="true"
                                        requiredMessage="Veuillez remplir le champ requis ville " /></td>
                            </tr>
                            <tr>
                                <td><b><h:outputText value="phone* : " /></b></td>
                                <td><h:inputText
                                        value="#{ClientBean.currentClt.phone}"
                                        id="phone"
                                        required="true"
                                        requiredMessage="Veuillez remplir le champ requis phone " /></td>
                            </tr>
                        </table>
                    </div>
                </rich:panel></td>
        </tr>
        <tr>
            <td><rich:panel id="panelAbonnement">
                    <f:facet name="header">
                        <h:panelGroup>
                            <h:outputText value="Abonnement"></h:outputText>
                        </h:panelGroup>
                    </f:facet>
                    <div>
                        <table>
                            <tr>
                                <td><b><h:outputText value="Date Debut* : " /></b></td>
                                <td><rich:calendar
                                        id="dateDebut"
                                        required="true"
                                        datePattern="dd/MM/yyyy HH:mm:ss"
                                        requiredMessage="Veuillez remplir le champ requis Date Debut"
                                        value="#{ClientBean.dateDebut}" /></td>
                            </tr>
                            <tr>
                                <td><b><h:outputText value="Date Fin* : " /></b></td>
                                <td><rich:calendar
                                        id="dateFin"
                                        required="true"
                                        datePattern="dd/MM/yyyy HH:mm:ss"
                                        requiredMessage="Veuillez remplir le champ requis Date Fin"
                                        value="#{ClientBean.dateFin}" /></td>
                            </tr>
                        </table>
                    </div>
                </rich:panel></td>
        </tr>
        <tr>
            <td><a4j:commandButton
                    onclick="#{rich:component('waitFormPanel')}.show()"
                    oncomplete="#{rich:component('waitFormPanel')}.hide()"
                    action="#{ClientBean.ajouterClient}"
                    styleClass="ajoutBtn"
                    value="ajouter"
                    limitRender="true"
                    render="msgs,panelClient" /></td>
        </tr>
    </table>
</form>

Knowing that my backing bean is sessionScoped.

For start replace the form with h:form