I was consulting my grammar book (A Dictionary of Intermediate Japanese Grammar), when I came upon the following passage (page 323):
Now this is all well and good. But it's a bit conflicting with an explanation in A Dictionary of Basic Japanese Grammar, in the section about ので (these books are in a series, by the same authors). Here's the relevant explanation (page 329-330):
This section is rather explicit that ので is unusable with requests, advice, suggestions etc. My Japanese teacher has also said that ので is unusable with advice.
I suppose then the question is, what is the truth? Is the original example sentence natural? Grammatical? Is there a deeper conclusion to draw here? Maybe から is inappropriate in such a polite request? Am I missing something very obvious?