No error here, the maker is Carl Maximillian Powalsky (fl 1753-1790); see Hintze page 140. Hintze doesn't illustrate Powalsky's mark, but describes it as "CMP in a leaf-form field". Note that Schmidt's mark is in a heart, not the leafy outline here; and once you know the bottom letter is a "P" not an "S", you can really see it.
Hope this helps!
PS: As it is now over 100 years old and in the public domain, Erin Hintze's classic (and still unsurpassed)
Die Breslauer Goldschmiede is available in its entirety as a
totally free downloadable PDF from Google Books.