Question: Why the numeric integration of Maple sometimes does not work?

Here I put two functions defined by piece-wise command and then using int(...,numeric) to take their integration but Maple computes only one while for the other one just gives the expression back. The integration domain is bounded, the function is bounded too so I don't think the reason is being divergent in the one that Maple is not computing it.

Is there any prepared command or package for Maple which computes the integrals like this or is better than just int(...,numeric)? Or I have to write an algorithm an force Maple to compute my integral using an algorithm given by myself?
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The codes in plain text:
 

int(piecewise(0 < -k5*x1*x2+k1*x1 < 1, 1, -k5*x1*x2+k1*x1 <= 0 and 1 <= -k5*x1*x2+k1*x1, 0)*piecewise(0 < -k5*x1*x2+k2*x2 < 1, 1, -k5*x1*x2+k2*x2 <= 0 and 1 <= -k5*x1*x2+k2*x2, 0), k1 = 0 .. 1, k2 = 0 .. 1, k5 = 0 .. 1, x1 = 0 .. 1, x2 = 0 .. 1, numeric);

int(piecewise(0 < x+y < 1, 1, x+y <= 0 and 1 <= x+y, 0)*piecewise(0 < y*x^2 < 1, 1, y*x^2 <= 0 and 1 <= y*x^2, 0), x = 0 .. 1, y = 0 .. 1, numeric);