On appeal, what is the effect of supplemental instructions on a jury?

On appeal, we may infer from questions asked by the jury that it was confused about a controlling legal principle. If that is the case, we inquire into whether the trial court, by its responses or supplemental instructions, eliminated that confusion. United States v. Petersen, 513 F.2d 1133 (9th Cir. 1975); Powell v. United States, 347 F.2d 156 (9th Cir. 1965). "The ultimate question is 'whether the charge taken as a whole was such as to confuse or leave an erroneous impression in the minds of the jurors.' " Powell v. United States, 347 F.2d at 158. We have also noted that "(i)t is no answer to say that the supplemental instruction was correct, so far as it went; or that it was to be read in the light of the original instructions and that these fairly presented the issues." Id.