problem with the derivation of the parameter q (p. 66)

[Andre Mayers]

Good day,

I am writing my thesis, and I spent the last two days trying  to find
out the missing step. If some body can explain  the equation 3.15, 
I will be very grateful. The problem is that  the probability of
failure given  the considered production is 

	                                  P(F, D, E)
P(F | D,E) =  ----------------------------------- 
                          P(F, D, E) + P(S, D, E) 


but the equation 3.15 gives (as far as I can see)

	                                  P(F, D)
P(F | D,E) =  ----------------------------------- 
                          P(F, D) + P(S, D, E) 

some body know why  ?

Thank you

Andre Mayers
Universite de Montreal