why are my solutions the same as initial values?

Hi. I build a 1D time-dependent model (transport of diluted species).

using conservative form.
convection transport mechanism
D=0;
u=-k/x^m; (k is a constant)
R=0;
no flux

iniitlal distribution: 1/(x^4*sqrt(2*pi)*log(sigma))*exp(-0.5*((log(x)-log(r_m))/(log(sigma)))^2)
k=4.92*10^(-14)/3600
m=3
sigma=1.2
r_m=0.034

But when I solve it, the solutions at all time are the same as initial values.

I also solve this problem with matlab, the solutions should be in the same shape but different values.

I don't know what had happened. The mph file is too big to be uploaded.

Would you please help me? Thanks very much.