If the Roserade already has more than 3 egg moves, there's a chance that Extrasensory will not be passed down.
Or atleast either of the two moves Exeggutor has. Say if your Roserade has Spikes, Sleep Powder and Giga Drain, and Exeggutor's move list has Extrasensory first, then Extrasensory will not be passed down.
The offspring should have the moves Leaf Storm, Spikes, Sleep Powder and Giga Drain.
This is because the male's.moves are first taken into consideration, and later the females.
The solution would be deleting one of the egg moves Roserade has.
Hope I helped!