This is a reply to the criticism from Engelhardt and Onoochin of our work (2011 Phys. Scr. 84 015009): a general argument for the possibility of different solutions in different gauges unrelated to gauge transformation; a result that has been given by Engelhardt and Onoochin using examples. For this reason we are not in any sense trying to refute the statements made by Engelhardt and Onoochin, instead we are offering a possible theoretical explanation of their results.Producción Científica de la Universidad Autónoma de Zacatecas UAZ