Optimize with constraints

[Giulia B.]

Dear all,

I need to minimize the following function L=(Xit*b- Y)^2 with nonlinear constraints.

I have imported the matrix Xit [556,28] and the vector Y[556]
so I need to find (the vector) b[28] subject to: b>=betaMAX (real colvector)

I wrote the following commands in mata but Stata reports a "redundant or inconsistent constraints".
This is my code:

mata

void maxme(todo,b,y,X,lnf,g,H)
{
lnf = (-y :+ X*b'):^2
}

init=J(cols(X),1,1)
s=optimize_init()

//build the constraint matrix
C = I(28)
c = exp(init):+betaMAX
Cc = (C, c)
optimize_init_constraints(s,Cc)

optimize_init_evaluator(s,&maxme())
optimize_init_evaluatortype(s,"v0")

optimize_init_argument(s, 1, y)
optimize_init_argument(s, 2, X)

optimize_init_evaluatortype(s,"d0")
optimize_init_which(s,"min")
optimize_init_params(s, init')

b = optimize(s)
b'

end

Thank you,
Giulia