ODE45 returns NaN

I wrote this code to plot the solution of an EDO, but MATLAB just returns NaN values. I can't find my mistake, can anyone help me?

tspan = [0 100];

v0 = 0;

[t,v] = ode45(@(t,v)(4800./(2200.*(1-0.8.^(t./40)))- 9.81),tspan,v0)

figure(1)

plot(t,v,'-o')

xlabel('Time (s)')

ylabel('Speed (m/s)')

Answer 1

[Alan Stevens]

t = 0 causes a problem. Try tspan = [0.1 100]; for example.

[Raquel Andrade]

It worked, thank you so much!!