incompatible vs incompatibility

incompatible is not a noun while incompatibility is a noun.

Word	Noun	Adjective	Verb	Adverb
incompatible	No	Yes	No	No
incompatibility	Yes	No	No	No

incompatible (noun)	incompatibility (noun)
	the quality of being unable to exist or work in congenial combination
	the relation between propositions that cannot both be true at the same time
	(immunology) the degree to which the body's immune system will try to reject foreign material (as transfused blood or transplanted tissue)

incompatible (adjective)	incompatibility (adjective)
used especially of drugs or muscles that counteract or neutralize each other's effect
not compatible
incapable of being used with or connected to other devices or components without modification
not suitable to your tastes or needs
of words so related that one contrasts with the other
used especially of solids or solutions; incapable of blending into a stable homogeneous mixture
not in keeping with what is correct or proper
not compatible with other facts
not easy to combine harmoniously