Custom field with underscore in link

[JoeT2627]

I apologize if this has already been asked a bunch of times.  It looks like other people have various forms of this question but I haven't found an answer that works for me.

I'm trying to put a custom field named person_key into a web link url.

I've tried various forms (12 so far) of the following:

https://www.my_site.com/ws/afco_car_kits.php?id=[[person_key]]

I want to link to my_site.com, subdirectory ws, file name afco_car_kits.php, with a GET parameter of id=xxx,

where xxx is from the person_key custom field in the contact record. 

So far, all my efforts have resulted in the correct URL, right up to and including ?id=.  The id parameter itself is always blank.

How to I write the link to pick up this custom field?  Thanks,

[JoeT2627]

I may have stumbled into a working answer.  I replaced the custom field name of "person_key" with "StoreKey" and it seems to be working.  Despite the examples on the constant contact site, is it possible that custom fields don't work with underscores in their name?

[Zoe_H · Accepted solution]

Hello @JoeT2627,

Yes, you are correct! The underscore was causing that error message and I do apologize for any inconvenience this may have caused. I will submit this over to our engineers for review.