Double Integral implementation in R

I've working on double integrals using mosaicCalc package in R. I'm having trouble getting the correct result of the second double integral.

This is the code of the first double integral which yields to the correct result (pi).

one = makeFun(1 ~ y + x)
bx.y = antiD(one(y = y, x = x) ~ y)
bx.yx = antiD(bx.y(y = 1+cos(x), x = 2) ~ x)
bx.yx(x = pi) - bx.yx(x = 0)
# [1] 3.141593

This is the second double integral which, according to Wolfram, its correct result should be 0.684853

one = makeFun(1 ~ y + x)
bx.y = antiD(one(y = y, x = x) ~ y)
bx.yx = antiD(bx.y(y = 1/2, x = sin(x)) ~ x)
bx.yx(x = 5*pi/6) - bx.yx(x = pi/6)
# [2] 1.047198