In my <Product>
I have:
<WixVariable Id="WixUILicenseRtf" Value="LICENSE.rtf" />
LICENSE.rtf
exists, and is an rtf file (I've tried saving with a few different programs in case it was a problem with one of them).
The file contains text (a whole license!), and the text is sensibly formatted.
Why then, is the License field of my installer blank?