Chevrolet Captive Box Failure

Good afternoon, I have a 2012 chevrolet, with 35000km, I am second owner is that since I bought it in some occasions to make the speed change from 2nd to 3rd kick and this does not always do it very occasionally, the question is whether this is normal since I had a venture that had the same fault and a specialist in box Normal in this trucks, already change the seleenoids of the camshaft but continue with the fault, thanks