I usually don't have trouble distinguishing when I should use an adjective and when an adverb. But today I wrote a sentence, and wasn't sure — actually, the longer I looked at it, the longer both variants looked wrong.
The sentence was about baking, and it said:
While it is best to use a recipe designed for a big batch, using a multiplied by three small-batch recipe is no more probable to fail than using the small-batch recipe for a single small batch.
While there is probably a way to state the whole idea more clearly, what nags me is the probable. It qualifies using, and using is, of course, a form of the verb "to use" (my English classes are too far in the past to be able to name the form). So maybe it should be the adverb probably, because it is qualifying a verb.
But this is not what my intuition says, and after years of being exposed to almost always grammatically correct English, I have learned to trust my language intuition. Maybe in this case I am mixing it up with the grammar rules for some other language, but I feel that probable and not probably is correct here. Which, of course, is contrary to the rule above. My best explanation is that the phrase "using X" is describing a process, not an action, and is therefore somehow a replacement for a noun, and "using X is no more probable to fail than" is correct for the same reason that "the option of using X is no more probable to fail than...", but this could be just a poor rationalization of my already formed opinion.
So which form is correct, and why?