I've found in my experience that tank raised clown fish, especially Ocellaris clown fish are hard to get to host to an Anemone.
For some reason they tend to like corals and rockwork to host to.
Maroon Clownfish, while much more agressive seem to host to an Anemone every time.
I don't know why but it's what I've found over the years. Just seems the tank raised Ocellaris clown's don't really know about hosting to an Anemone, it seems like it's just not natural for them.
90 Gallon Drilled Glass Tank w/ Corner Overflow: 492w (2x 150w 14,000K MH, 2x 96w Actinic CF) Coralife Aqualight Pro | Custom 34x15x15 Sump/Refugium | SWC Skimmer | Coralife Turbo-Twist 6x UV Sterilizer | Maxi-Jet Power Head w/Sure Flow Upgrade Kit | 120lbs of Live Rock | 100lbs of Live Sand