Cannot add direct child without default aggregation defined for control sap.m.GenericTile

Hey,

I want to create a Generic Tile for a SAPUI5 Project. But unfortunately, it throws me this error: "Cannot add direct child without default aggregation defined for control sap.m.GenericTile at Q". How can I fix this error? Below you see my coding.

Kind regards,
Martin

<mvc:View controllerName="eAUb.controller.Sachbearbeiterlisten" xmlns:mvc="sap.ui.core.mvc" xmlns="sap.m">
<App>
<pages><Page title="{i18n>title}">
<content>
<GenericTile header="{i18n>appTitle}">
<TileContent>
<ImageContent src ="sap-icon://outbox" />
</TileContent>
</GenericTile>
</content>
</Page>
</pages>
</App>
</mvc:View>