validate zip code

I am trying to validate canada zip code using the following function in asp:

[a-zA-Z]\d{1}[a-zA-Z]\b \d{1}[a-zA-Z]\d{1}
(it works in .NET)

For some reason space is not recognized.
I also tried using \x20 to represent space.
It is also not working.
Does anyone knows what is the issue and how to fix it?

Thanks much.

PS canadian zip example: Z5Z 5Z5
char(1) integer char(1) space integer char(1) integer