If you want to use the lucca-ui styling for your inputs, here is the correct synthax to employ
<div class="lui {sizing} field"> <!-- sizing is short, regular, long, fitting, etc... -->
<span class="lui input">
<input ng-model="myVar" {name="name"} {placeholder=} {ng-required}> <!-- any king of input works, even the luid-date-picker-popup or luid-user-picker -->
<label>Label</label> <!-- always put the label after the input -->
</span>
<small class="message helper">a message to display bellow the input</small>
<small class="message error" ng-show="form.name.$invalid">the input is invalid</small>
</div>