How to correct the regenerated plot of given analytical solution of ODE?

for

for

The analytical solution for this ODE is given belown and written as MATLAB in code routine:

for

t = -log(1-a)/((K1+K2)*(B-1)) + log(1-(a/B))/((K1+(K2*B))*(B-1)) + (K2*log(1+((a*K2)/K1)))/((K1+(K2*B))*(K1+K2));

and for

t = -(1/K3)*(log((1-a)/0.7))+tc; 

where,

tc = -log(0.7)/((K1+K2)*(B-1)) + log(1-(0.3/B))/((K1+(K2*B))*(B-1)) + (K2*log(1+((0.3*K2)/K1)))/((K1+(K2*B))*(K1+K2));

other constants used are:

R = 8.314;
T = 450;
B = 0.4:0.54;
A1 = 2.101e9;
A2 = -2.014e9;
A3 = 1.960e9;
delE1 = 8.07e4;
delE2 = 778e4;
delE3 = 5.66e4;
K1 = A1*exp(-delE1/(R*T));
K2 = A2*exp(-delE2/(R*T));
K3 = A3*exp(-delE1/(R*T));
k = K1/K2;

I regenerated the plot for from the the given solution:

But the actual plot of the given solution is

where I'm doing WRONG?

Please guide me.

Thanks