### Function solve doesn't work corrctly

Dear users,
I have a problem with function solve.

I have a system and I want resolve it by formula Ax=b.
I generate correctly A and b matrix, and I call function

solve(A,b,solution,DECOMP_LU);

the solution is completly wrong.
I try resolve the system using matlab and the solution is different.

I ask you...why does the function "solve" not work?