Hi Hao Ding.
Thanks you soo much for your help. I have restricted the problem only to the first and third constraint and the issue was resolved. You are right, the first, second and fourth constraint express the same.
Although, the BFGS method still runs ver slow, maybe due to the complexity of the objetive function. I will follow your past recomendation “try other optimization method first, and use the results as starting points for BFGS to refine the results.”
Again, thanks very much for your help.