trouble using URL variable

I have 2 pages where I am using a URL variable to display a product name and price on the page, as well as bring that information into my Add to Cart button.

On one page it works great, on the other I cannot get it to work. I can't tell what i've done wrong, any help is greatly appreciated.

Working page - https://ltac.org/convention/registration.php click any of the registration items and it takes you to the page with the A2C button and populates the URL variable.

Non-working page - https://ltac.org/registration/cti-registration.php - click any of the class registrations, and it takes you to the A2C page, but no URL variable.

Thank you for your help!

You have a hidden form element named: LTAC14_1_ID_Add
That needs to have its value set to the url parameter. It appears to be set on the working page but is blank on the one that isn't working. I can't see the code, but if you uploaded a copy of each page I could be more specific.

I wasn't able to find the blank parameter from above. I have attached both pages.

registration-form-nw = the nonworking page, located at www.ltac.org/registration/registration-form.php

registration-form-w = the working version, located at www.ltac.org/convention/registration-form.php

Thanks for taking a look at this for me!

The issue is that you aren't sending the appropriate RegID value to the page. If you look at the working page it goes to something like:
https://ltac.org/convention/registration-form.php?RegId=ConvRegMFT

But the non working page just goes to:
https://ltac.org/registration/cti-advancedclaims-member.php

The recordset is set to filter based on the RegID passed in the URL and it won't work without it the way it is set up now. The key is making sure the Recordset on the page is filtered to the correct value by either passing in the RegID, or by doing the filter manually if each will have its own page.