Trust Level error when publishing MVC application

I need to publish an ASP.NET MVC application to a LocaWeb server. But when I publish, the server displays the following message:

I'vetriedputtingtags

<securityPolicy><trustLevelname="Medium" policyFile="web_mediumtrust.config" />
</securityPolicy>
<trust level="Full" originUrl="" />

But when I put it, the server returns this message:

What should I do?