Buff / debuff stacking?

[hylozoist]

<DIV>I find that my steal breath / maelstrom line does not stack with the wizard ice debuff line (icy coil / icicles).  This has happened both before the revamp and after, although I have not been in an group with one recently, but rather only in raids.  Has this even been addressed?</DIV> <DIV> </DIV> <DIV>Further, the "seal" line seems to encounter many problems.  While Seal of Ebon Thought seems to stack fine with wizards, I have problems with Illusionists, Coercers and even Conjurors' group buff lines.  Is this intended, and/or has this been fixed?</DIV> <DIV> </DIV> <DIV> </DIV>