boundary condition for flat plate
 

I,m having problem with imposing proper boundary conditions for simple-based finite volume code for incompressible flow
by setting the inlet velocity u=1 and implementing the boundary condition suggested by versteeg( in his book:uj=m_in/m_out*u_j-1) I couldn't get a converged solution. by implementing this boundary condition I get a very large negative sources in the end plate cell column for the pressure correction equation. and these sources results in a large p_prime gradients near the end of the wall.
I have to mention that neuman boundary condition have been used for all 4 side of the domain.
any suggestions for a better and proper boundary conditions??????