Could anyone please help me find the error in the code

Question

I have a problem with DSolve and the following code:

DSolve[{D[Ψ[x], x, x] == κ^2 Ψ[x],
  Ψ[0] == Ψs, Ψ[Infinity] == 0}, Ψ, x]

The error getting displayed in Mathematica is:

DSolve::bvlim: For some branches of the general solution, unable to 
compute the limit at the given points. Some of the solutions may be lost.

Answer 1

ode=w''[x]==k^2*w[x]
Ic={w[0]==ws,w[L]==0}
sol=DSolveValue[{ode,Ic},w[x],x]
Assuming[k>0,Simplify[Limit[sol,L->Infinity]]]

Gives

Exp[-kx] ws