Hmm. The males and females are not just tell-apartable from finnage. There is major colour difference when mature. The males are more orange, where the females are a pale colour.
[URL="http/www.aquahobby.com/gallery/e_silvertip.php"]http/www.aquahobby.com/gallery/e_silvertip.php[/URL]
The photo isn't great but you can see a male on the left showing orange skin colouration. The fish in the middle is showing the pale colouration of females. The others in the photo have been washed out too much by the flash of the camera.
What is your water temp? Wonder if the tamp of your tank may be slightly low and not stimulate breeding.
Used a pippette to remove the fry from the breeding tank yesterday - and it took me AGES!! removed close to 100 fry. I wonder how many will make it to larger size. Removed them so that I could give the plastic tank a good clean. There were some eggs that developed fungus, so I wanted to remove these preventing the fish from getting the fungus.
Perhaps you could post photos of your fish so I could have a look, see If I could sex them for you.