nuclear RNA extraction from egg, 3 instar, adult?

Hello every1,
Now I want to arrest the primary transcripts in the nucleus by
extracting all the nuclear pellet, after failed to use the total RNAs
several times. And it supose that my interested transcripts were rare
in the total RNAs extraction, so the abundance of these transcripts
may increase by extracting nuclear RNA from egg, larva and adult of
fruit fly but not certain cultured cells( e.g. S2).
Can it be achieved only by separating cells from all tissues not
considering cell types? Any suggestions will be greatly appreciated!
whitedolphin