Question: intersection point

Hey everybody,

for some reason I dont get for the following problem any answer, with other data it worked, but not whit this!? and i know that there is a intersection point!!

> S1 := proc (t) options operator, arrow; F[1](t)*m[1]*(1-F[2](t)) end proc;
> S2 := proc (t) options operator, arrow; F[2](t)*(m[2]+F[1](t)*m[1]) end proc;
> F[1] := proc (t) options operator, arrow; (1-exp(-(p[1]+q[1])*t))/(1+q[1]*exp(-(p[1]+q[1])*t)/p[1]) end proc;
> F[2] := proc (t) options operator, arrow; piecewise(tau < t, (1-exp(-(p[2]+q[2])*(t-tau)))/(1+q[2]*exp(-(p[2]+q[2])*(t-tau))/p[2]), t> s1 := proc (t) options operator, arrow; eval(S1(t), [p[1] = 0.6917e-1, q[1] = .409, m[1] = 100000, tau = 6, p[2] = 0.723e-1, q[2] = .4451]) end proc; s2 := proc (t) options operator, arrow; eval(S2(t), [p[1] = 0.6917e-1, q[1] = .409, m[1] = 100000, tau = 6, p[2] = 0.723e-1, q[2] = .4451, m[2] = 140822.7]) end proc; s1(t); s2(s); fsolve(s1(t) = s2(t), t, avoid = {t = 0});

thanks a ot in advance! nora