What tyre for Narrow Deep V?

Hi, I've got a DP18 and having a bit of trouble with it. I can get the tyre on (23c armadillo) but there is an air leak between the edges of the rim and tyre and it goes flat within a minute.

I'm guessing it's because the tyre has been on a wide rim for so long (2000km) that it won't sit on such a narrow rim. Also tried a 25c cheap tyre and that is the same.

After much swearing I have given up and am asking all you experts on the forum, is there something wrong? or if not, what tyre would you use for this rim?

thanks in advance.

I had the same! All your doing is nipping the inner tube! There is an art to fitting tyres and tubes on those bloody nice rims!