help with ~ as exclusion pattern operator

[unpingco@xxxxxxxxxxxx (Jose Unpingco)]

hi,

I have a directory of files 

    ssp0.10coef1.txt
    ssp0.20coef1.txt
    ssp3299.txt
    ssp3300.txt
    ssp3301.txt
    ssp3302.txt
    sspeofproj.eps
    sspgi1.txt
    sspsamples.eps

Why is it that when I do

% ls ssp*t~*co*

I don't get 

    ssp3299.txt
    ssp3300.txt
    ssp3301.txt
    ssp3302.txt
    sspgi1.txt

Instead I get

    zsh: no matches found: ssp*t~*co*

I don't get it. I read the manual page on the ~ operator.

Thanks.