can any one know the reason about this

hi

my question is i did the route determination. But it is not coming automatically in the sales order. What could be the reason. These prerequisties i maintained

1)depature country of ship to party (taken from shipping point)

2)shipping conditions from sales doc

3)transportation groups of mm

4)destination country of ship to party

5) weight group

all these i maintained but it is not coming automatically can any know about the reason about this. Give the specific reason.

thanks in advance