Logic element to CNF

Question

I have a big problem with a XNOR element expression. I analyzed the circuit in LOGISIM and it wrote me the minimal type of CNF which is (A + B + D)(A + B + ~C)(~B + C + ~D)(~A + C + ~D). The base XNOR expression looks like this Y = ~(A + B) XNOR ~(C+~D) The minimal DNF type of this XNOR expression is this (~A ~B ~CD + B*~D + BC + A ~D + A*C) We sat on this for 3 whole days and can't treat this expression to that final CNF form. Could be so kind and make a little attention to this expression?