Eu estou tentando ter uma lista suspensa de submenu dentro de uma lista suspensa, usando a estrutura MaterializeCSS. Eu tentei com o código a seguir, mas não funcionou.

<!-- this the main dropdown -->
<ul id="MainDropDown" class="dropdown-content">
    <li><a href="#" class="dropdown-button" data-beloworigin="true" data-contrainwidth="false" data-gutter="30" data-alignment="right" data-activates="drop1">Dropdown1<span class="right caret">&#9658;</span></a></li>
    <li><a href="#" class="dropdown-button" data-beloworigin="true" data-contrainwidth="false" data-gutter="30" data-alignment="right" data-activates="drop2">Dropdown2<span class="right caret">&#9658;</span></a></li>
    <li><a href="#" class="dropdown-button" data-beloworigin="true" data-contrainwidth="false" data-gutter="30" data-alignment="right" data-activates="drop3">Dropdown3<span class="right scaret">&#9658;</span></a></li>   
</ul>
<ul id="drop1" class="dropdown-content">
    <li><a href="#">Create</a></li>
</ul>
<ul id="drop2" class="dropdown-content">
    <li><a href="#">Create</a></li>
    <li><a href="#">Update</a></li>
</ul>
<ul id="drop3" class="dropdown-content">
    <li><a href="#">Create</a></li>
</ul>