Failed to find a solution

Hello
I am a new user, and I am very impressed, Comsol is perfectly simulated in chemical reactor design
And when I began using of Comsol I have some problems with it.
And I have a set of PDE's in Dehydrogenation Reactor, and we decided to solved it by comsol
But I get this matter (( Failed to find a solution. Maximum number of Newton iterations reached.
There was an error message from the linear solver. The relative residual (5.8e+006) is greater than the relative tolerance. Returned solution is not converging.))

plz. Help me...
--
Omar S. Lateef
omar@greenpcbtronics.com
00964 7704852473