Question: Very urgent!!I was try to use the command "expand" but it going error, (in property/ConvertProperty) invalid input: PropRange uses a 2nd argument, b, which is missing

Just like the title described, I have encountered an error when I use the command "expand". Actually, I just follow the example, but it doesn't work. Please help me or tell me how can I solve it in other commands.

restart;
alias(epsilon = e, omega = w, omega[0] = w0, t[1] = t1, t[2] = t2); e := proc (t1, t2) options operator, arrow; e end proc; w0 := proc (t1, t2) options operator, arrow; w0 end proc; a := proc (t1, t2) options operator, arrow; a end proc; f := proc (t1, t2) options operator, arrow; f end proc; mu := proc (t1, t2) options operator, arrow; mu end proc;
ode := (D@@2)(u)+2*mu*e*D(u)+w0^2*u+e*w0^2*u^3-e*f*cos(omega*t) = 0;
                                               2  
     @@(D, 2)(u) + 2 mu epsilon D(u) + omega[0]  u

                          2  3                             
        + epsilon omega[0]  u  - epsilon f cos(omega t) = 0
e_oredr := 1;
ode := simplify(subs(D = sum('e^(i-1)*D[i]', 'i' = 1 .. e_oredr+1), ode), {e^(e_oredr+1) = 0});
 / 3         2                                                 
 \u  omega[0]  + 2 (epsilon D[2] + D[1])(u) mu - cos(omega t) f

                  \                   2                   
    + 2 D[1, 2](u)/ epsilon + omega[0]  u + D[1, 1](u) = 0
simplify(collect(%, e), {e^(e_oredr+1) = 0});

u := sum('v[i]*e^i', 'i' = 0 .. e_oredr);
                      epsilon v[1] + v[0]
ode := simplify(collect(ode, e), {e^2 = 0});
for i from 0 to e_oredr do eq[i] := coeff(lhs(ode), e, i) = 0 end do;
                       2                         
               omega[0]  v[0] + D[1, 1](v[0]) = 0
       3         2           2                       
   v[0]  omega[0]  + omega[0]  v[1] + 2 D[1](v[0]) mu

      - cos(omega t) f + 2 D[1, 2](v[0]) + D[1, 1](v[1]) = 0
remove(has, lhs(eq[1]), cos); convert(%(t1, t2), diff);
eq[1] := %-convert(f*cos(sigma*t2+t1*w0), 'exp');

v[0] := A(t2)*cos(w0*t1+B(t2)); convert(%, 'exp'); v[0] := unapply(%, t1, t2);
                         /1                             
       (t1, t2) -> A(t2) |- exp(I (omega[0] t1 + B(t2)))
                         \2                             

            1                              \
          + - exp(-I (omega[0] t1 + B(t2)))|
            2                              /

expand(eq[1]);
Error, (in property/ConvertProperty) invalid input: PropRange uses a 2nd argument, b, which is missing
collect(%, exp(I*w0*t1));
Error, (in collect) invalid 1st argument proc (t1, t2) options operator, arrow; A(t2)*((1/2)*exp(I*(w0*t1+B(t2)))+(1/2)*exp(-I*(w0*t1+B(t2)))) end proc
coeff(%, exp(I*w0*t1));
map(proc (x) options operator, arrow; x*exp(-I*B(t2)) end proc, %);
combine(%, 'exp');
subs(I*B(t2) = I*sigma*t2-I*C(t2), B(t2) = sigma*t2-C(t2), %);
conds := combine(%, 'exp');
                               0