Because while Schildt is indeed a good author, in that he writes interesting texts, he very frequently gets his facts wrong. Here's what a page about the C and C++ standards has to say about his book "The Annotated ANSI C Standard":
In fact, the reason this book is recommended is simply that it's the cheapest way of acquiring a copy of the standard.Herbert Schildt is not held in wide regard by knowledgeable C and C++programmers, and this is the only book with his name on it most of them would ever recommend. The format of the book places the text of the standard on the left hand pages side-by-side with Schildt's annotations on the right hand side.
While many of Schildt's comments are incorrect and flatly contradict the actual text of the standard on the facing page, the standard itself is complete except for one missing page.
Some more:
http://www.lysator.liu.se/c/schildt.html
http://herd.plethora.net/~seebs/c/c_tcr.html