On line 253. Was the delegation successful in their mission? Why or why not?

No, they went with all good intentions to speak with the minister, but in the end they didn't even broach the subject because they found themselves unable to speak with him while he wore the veil.

"Yet, though so well acquainted with this amiable weakness, no individual among his parishioners chose to make the black veil a subject of friendly remonstrance. There was a feeling of dread, neither plainly confessed nor carefully concealed, which caused each to shift the responsibility upon another, till at length it was found expedient to send a deputation of the church, in order to deal with Mr. Hooper about the mystery, before it should grow into a scandal. Never did an embassy so ill discharge its duties. The minister received them with friendly courtesy, but became silent, after they were seated, leaving to his visitors the whole burden of introducing their important business. The topic, it might be supposed, was obvious enough. There was the black veil swathed round Mr. Hooper's forehead, and concealing every feature above his placid mouth, on which, at times, they could perceive the glimmering of a melancholy smile. But that piece of crape, to their imagination, seemed to hang down before his heart, the symbol of a fearful secret between him and them. Were the veil but cast aside, they might speak freely of it, but not till then. Thus they sat a considerable time, speechless, confused, and shrinking uneasily from Mr. Hooper's eye, which they felt to be fixed upon them with an invisible glance. Finally, the deputies returned abashed to their constituents, pronouncing the matter too weighty to be handled, except by a council of the churches, if, indeed, it might not require a general synod."