mates automatically suppress and fix mate it self

Dear All.

What mistake did I don,t,in SW2012 only i am facing this kind of problem,

i have replace few parts from my ass,then i start edit it ,while i find all of my previous mate all suppressed and fix mate it self ,i have try to do unsuppressed it but it can't ,

what is the problem here.

Thanks

SolidworksGeneral