Boundary Value Problem\ Symbolic solution

I wanted to solve a sturm-liouville boundary value problem using the symbolic command dsolve, and I wanted to avoid using character vectors input as MATLAB suggests. but this wrong asnwer apears when using the classical symbolic way:

Answer 1

[Paul]

Need to use sym(pi)

syms y(t)
cond = [y(0)==0,y(1)==0];
X = dsolve(diff(y,t,2)+sym(pi)^2*y==0,cond)

X = 

[Sara Slameh]

Thank you so much!