Airport express using WPS to Linksys Wireless router?

I have a Linksys Wireless router set up to server wireless signal to macs and PCs in my office. It works great, but one of the far offices can't get enough signal.

I bought an airport express assuming I could use it as a repeater in this office.

I'm having some trouble connecting it (config goes great, then when i try and enable WPS mode - entering the current Linksys ID it just flashes orange after restart).

Any tips? Should this be possible?

.dave