We need to compute some integral, containing product of some "regular" function (e.g. gaussian)
and Dirac delta-function. The problem is that argument of delta-function is itself a function.

A simplified example is

d1:=s->int( g(x,5,0.025)*Dirac( s-f1(x) ) , x=0..infinity);

By trials and errors, we figured out that Maple runs such calculation successfully
when this function is very simple and fails in more complex cases, i.e., integration  returns zero.