Question

In chapter 5, halakhah 3, Maimonides writes: “If one roofed it with foods, it is invalid, because they are susceptible to impurity. Bundles of figs with figs in them; clusters of grapes with grapes in them; brooms with dates in them; and likewise anything similar. We consider: if the waste is greater than the foods, one may use them for sekhakh, but if not, one may not use them for sekhakh. If one used vegetables for sekhakh such that, if they dry out, they will wither and nothing substantial will remain of them, even though they are now moist, their place is considered as though it were empty air, as though they were not there.” That is, if there is a majority of waste over the foods, which are invalid sekhakh, it is valid. But regarding a sukkah under a tree, in halakhah 12 he writes: “One who makes his sukkah under a tree is as though he made it inside a house. If he spread over it the leaves and branches of the tree and roofed over them, and afterward cut them, then if the valid sekhakh was greater than they were, it is valid. But if the sekhakh that was valid from the outset was not greater than they were, he must shake them after cutting them so that it will be made for the sake of a sukkah.” That is, if one used attached sekhakh together with valid sekhakh, it is invalid even if there is a majority of valid sekhakh, and only if he cuts them does the majority of valid sekhakh validate the cut sekhakh, which was invalid because of the rule of “make it, and not from something already made”—which seems to contradict what he wrote in halakhah 3?