Re: Waki ga nai
This is, what I found:
わけがない 《訳がない(P); 訳が無い; わけが無い》 (exp) (uk) there is no way that ... (expresses speaker's belief that something is impossible);
Having no living dicionary around at the moment I asked Mr. and Mrs. Google and found Mr. Breens translation in different places.
I also checked it with "Ulrich Apels Japanisch-Deutsches Wörterbuch" and found the same meaning:
"It is not possible ... "
And yes, please: Christian Tissier is "approachable" and tries to answer questions as best as he can.