mx:DateCooser sometimes dissapears

Hi all,

I am using the mx:DateChooser Component in a CalloutButton.
Problem is - sometimes the DateChooser displays no Content.

Any ideas how this can happen and be avoided?

[cid:image001.png [ at ] 01CFE946.18B9DC50]
<Common:VccCalloutButton id="calloutButton"
label="PDF ERZEUGEN"
verticalPosition="before"
horizontalPosition="middle"
emphasized="true" skinClass="Skins.VccButtonSkin">
<!-- Setting callout layout to "VerticalLayout" -->
<Common:calloutLayout>
<s:VerticalLayout/>
</Common:calloutLayout>

<!-- Setting a set of components to callout's content as an Array -->
<Common:calloutContent>
<s:Group width="100%" height="100%" id="calloutContentGroup">
<s:VGroup width="200" paddingTop="10" id="prodOk">
<s:Label text="Wählen Sie das virtuelle Produktionsdatum" maxDisplayedLines="2" lineBreak="toFit" width="180" paddingLeft="10" paddingRight="10" textAlign="center"/>
<mx:DateChooser width="100%" id="prodDateChooser" change="onMakePdf(event)"/>
</s:VGroup>
</s:Group>
</Common:calloutContent>
</Common:VccCalloutButton>

Regards,
Andi