Include SharePoint Control in XSLT

Hi,

I am trying to include a SharePoint control inside XSLT (DataFormWebPart).

I have this declaration on my page:

<%@ Register Tagprefix="spswc" Namespace="Microsoft.SharePoint.Portal.WebControls" Assembly="Microsoft.SharePoint.Portal, Version=15.0.0.0, Culture=neutral, PublicKeyToken=71e9bce111e9429c" %>

And in my stylesheet declaration:

xmlns:spswc="Microsoft.SharePoint.Portal.WebControls"

However, I always get an error about an unknown server tag. If I declare it outside XSLT it works perfectly.

Any ideas?

Thanks,

RP