Question: ordered product of creation and annihilation operators - expand

Hello,

I am trying to find the product of three groups of creation and annihilation operators. After completing the input of the groups, Maple fails to give me the product of the operators (value of sigma^3) as shown below. What I need is for Maple to give me the ordered product of the three groups, but the "expand" command (lowercase 'e') fails to produce any output. Appreciate any help.

> with(Physics);
> Setup(mathematicalnotation = true);
print(`output redirected...`); # input placeholder
                 [mathematicalnotation = true]
> am1 := Annihilation(p, 1, notation = explicit);
print(`output redirected...`); # input placeholder
                        am1 := a-[p[1]]
> ap1 := Creation(p, 1, notation = explicit);
print(`output redirected...`); # input placeholder
                        ap1 := a+[p[1]]
> op1 := am1*exp(-i*p[1]*x);
print(`output redirected...`); # input placeholder
                 op1 := a-[p[1]] exp(-i p[1] x)
> op2 := ap1*exp(i*p[1]*x);
print(`output redirected...`); # input placeholder
                 op2 := a+[p[1]] exp(i p[1] x)
> am2 := Annihilation(p, 2, notation = explicit);
print(`output redirected...`); # input placeholder
                        am2 := a-[p[2]]
> ap2 := Creation(p, 2, notation = explicit);
print(`output redirected...`); # input placeholder
                        ap2 := a+[p[2]]
> op3 := am2*exp(-i*p[2]*x);
print(`output redirected...`); # input placeholder
                 op3 := a-[p[2]] exp(-i p[2] x)
> op4 := ap2*exp(i*p[2]*x);
print(`output redirected...`); # input placeholder
                 op4 := a+[p[2]] exp(i p[2] x)
> am3 := Annihilation(p, 3, notation = explicit);
print(`output redirected...`); # input placeholder
                        am3 := a-[p[3]]
> ap3 := Creation(p, 3, notation = explicit);
print(`output redirected...`); # input placeholder
                        ap3 := a+[p[3]]
> op5 := am3*exp(-i*p[3]*x);
print(`output redirected...`); # input placeholder
                 op5 := a-[p[3]] exp(-i p[3] x)
> op6 := ap3*exp(i*p[3]*x);
print(`output redirected...`); # input placeholder
                 op6 := a+[p[3]] exp(i p[3] x)

> sigma3(x) :=[op1+op2]*[op3+op4]*[op5+op6];
print(`output redirected...`); # input placeholder
     sigma3 := Physics:-*(

       [a-[p[1]] exp(-i p[1] x) + a+[p[1]] exp(i p[1] x)],

       [a-[p[2]] exp(-i p[2] x) + a+[p[2]] exp(i p[2] x)],

       [a-[p[3]] exp(-i p[3] x) + a+[p[3]] exp(i p[3] x)])