HP49-50G Integral of (0,infinity ,e^-X*SIN(X),X)

[Gil]

I try to integrate
'S(0,infinity,e^-X*SIN(X),X)' on the stack.

a) Then —>NUM
and Output:
"Num Error
Undefined name"

b) or
EVAL —> NUM
and output ok =1/2 is given.

But I can evaluate directly with a) (—>NUM)
'S(0,5,e^X,X)' without any problem.

Is it normal?

Gil