<p dir="auto">I cannot build the code after upgade to material-ui 1.0.0-beta.18.<br>
<a target="_blank" rel="noopener noreferrer nofollow" href="https://user-images.githubusercontent.com/20197580/32212958-cb9228b8-be4b-11e7-8b84-b687acbe6d3a.png"><img src="https://user-images.githubusercontent.com/20197580/32212958-cb9228b8-be4b-11e7-8b84-b687acbe6d3a.png" alt="image" style="max-width: 100%;"></a></p>
<p dir="auto">I have checked the code see that TransitionProps are using children with type React.ReactElement, but CollapseProps are using a diffirence type React.ReactNode. Could it problem?</p>


<ul class="contains-task-list">
<li class="task-list-item"><input type="checkbox" id="" disabled="" class="task-list-item-checkbox"> I have searched the <a href="https://github.com/callemall/material-ui/issues">issues</a> of this repository and believe that this is not a duplicate.</li>
</ul>
<h2 dir="auto">Your Environment</h2>

<table role="table">
<thead>
<tr>
<th>Tech</th>
<th>Version</th>
</tr>
</thead>
<tbody>
<tr>
<td>Material-UI</td>
<td>1.0.0-beta.18</td>
</tr>
<tr>
<td>React</td>
<td>16.0.0</td>
</tr>
</tbody>
</table>
<p dir="auto"><a href="https://material-ui-1dab0.firebaseapp.com/#/" rel="nofollow">https://material-ui-1dab0.firebaseapp.com/#/</a></p>

<h3 dir="auto">Problem description</h3>
<h3 dir="auto">Link to minimally-working code that reproduces the issue</h3>
<p dir="auto">I see error<br>
<a target="_blank" rel="noopener noreferrer nofollow" href="https://cloud.githubusercontent.com/assets/590985/24245539/5454c984-0fd4-11e7-83a4-80cb67fd04af.png"><img src="https://cloud.githubusercontent.com/assets/590985/24245539/5454c984-0fd4-11e7-83a4-80cb67fd04af.png" alt="image" style="max-width: 100%;"></a></p>

<h3 dir="auto">Versions</h3>
<ul dir="auto">
<li>Material-UI: 1.0-alpha</li>
<li>React: 15.4</li>
<li>Browser: IE 11</li>
</ul>