ODE with BVP problem (getting an error I do not understand)

Hello I'm having trouble with a BVP question.

My code is:

function [x2,u2] = Problem3()

function dxdz = odeRHS(z,Z)

dxdz = [Z(2); Z(3); Z(4); (z-z^2)];

end

function bc = odeBCs(za,zb)

bc = [ za(1) za(2) zb(1) zb(4) - 0.8 ] end

solinit = bvpinit(0,0); %used bvp4c to solve the BVP Z = bvp4c(@odeRHS,@odeBCs,solinit); u2=Z.y(1,:) x2=Z.x

plot(x2, u2, 'g', 'LineWidth', 2) grid on

I keep getting these errors though.

Error using bvpinit (line 73) The entries of x must satisfy a = x(1) ~= x(end) = b.

Error in Problem3 (line 17) solinit = bvpinit(0,0);

Any help would be greatly appreciated !!