Form is always disabled

Form validation does not work correctly. I have following template, note submit button is outside of the form

    <ion-content class="has-header padding">
        <ion-list ng-if="!isConnectionError">
            <div class="margin-top-50 padding-top padding-bottom center">
                <h3>{{'confirm_send_receipt' | translate}}</h3>
            <form name="receiptForm" id="receiptForm">
                <label class="item item-input">
                    <i class="icon ion-email placeholder-icon"></i>&nbsp;&nbsp;
                    <input name="email" ng-model="" type="email"
                           placeholder="{{'email' | translate}}">
    <ion-footer-bar class="footer-bottom-margin">
        <div class="col center">
            <button ng-click="skipButtonClicked()" class="button button-block button-stable footer-buttons">
                {{'skip' | translate}}
        <div class="col center">
            <button form="receiptForm"
                    class="button button-block button-assertive footer-buttons">
                {{'send_receipt' | translate}}

This button is always disabled even if I write correct email address.