be patient. give the clowns a bit of time to see if they will accept the anemone. The anemonies recommended for Amphiprion Percula are as follows: Heteractis Crispa, Heteractis Magnifica, Stichodactyla gigantea.
Stichodactyla Mertensii - Mertens' Sea Anemone
Stichodactyla gigantea - Gigantic Sea Anemone
Heteractis Magnifica - Magnificent Sea Anemone (Radianthus ritteri)
Heteractis Crispa - Leathery Sea Anemone
Hope some of this helps. above are the names of anemones your clowns may accept. good luck, give it about 3 to 6 months for the young fish to mature.