Vishaka

I found a fidelity between initial and final state (pure). Now when t=0 , I am getting F=1 When t=pi/2(90 degree) i am getting F= (4.5)(10^-5) But my teacher says this is wrong and I should get F=1. Why should I get 1 and Why am I not getting 1? What's wrong with my calculation? Here alpha is the coherent state and its value is sqrt 5 Adobe Scan 31-Aug-2021 (2).pdf