Base Wont Recognize Glass Break Sensors

Are you pressing the button on the sensor to put it into pairing mode?

Yep.

You're referring to the test button on top I assume?

Yeah.  Usually they add without incident.  Have you tried new batteries?  Maybe you got some that arrived dead.

I'll try it. The light illuminates when I press the button.

I have two, and neither one wlll register.

I wonder if you got the wrong glass break sensors.  In case you aren't aware there are 2 models of SS, the older and the newer.  The sensors are not interchangeable.

I purchased them from Simplisafe.

These are the ones I received (not these exact sensors, of course).

https://www.ebay.com/i/223744357967?chn=ps&norover=1&mkevt=1&mkrid=711-117182-37290-0&mkcid=2&itemid=223744357967&targetid=882904020427&device=c&mktype=pla&googleloc=9025384&poi=&campaignid=6469981122&mkgroupid=86285324342&rlsatarget=pla-882904020427&abcId=1141176&merchantid=6296724&gclid=Cj0KCQjwka_1BRCPARIsAMlUmErx-CiRbC0wtqoegiGqNU4P4HPZRq3L-k83W-33DRrnPYA6qowYSIEaAsAeEALw_wcB

^ Here's the link to the two different systems - the older system, SS2 is called the "Original Simplisafe", the newest, SS3 is called the "All New Simplisafe" - click on the base station that matches yours, to see/purchase options for the corresponding sensors for that base station.  

https://simplisafe.com/alarm-sensors

If you have the correct sensors, call SS and ask for assistance in getting them working correctly.