a desolve question....

[webmasterpdx]

When I look at the help examples for desolve, the double derivative is expressed using the ' character....as in:
desolve(y''+y=0,y)
Now, when I cut and paste the example, it works, but when I try to type the ' char myself, it fails....I was getting the ' char from the shift-9 menu.....which obviously isn't the same ' char as is used in the examples.
How do I generate the correct ' character?
Thx
-Donald