EDIT: I solved it. Sorry for waste of time! :(
Here is the function ψ[x]:
0.0000551056 a0.25 (30240. a0.5 x - 80640. a1.5 x3 +
48384. a2.5 x5 - 9216. a3.5 x7 + 512. a4.5 x9)(-((a x2)/2))
I am trying to integrate ψ[x]*ψ[x] over all space (-infinity to +infinity).
I don't get any error...