Help with HTML code

I have an HTML code that I am trying to attach to my website to link to a payment portal.
I use the Add.More.HTML code feature and copy the code in. The button appears.
I publish the site and try to use the button, but when I click on the button, it just disappears.
The payment portal I am using is Payeezy through First Data.
Any help with this??
Should I put the HTML code on here for those to look at it?

Hi David,

Can you please provide a link to the page with the html code?

Thanks,
Itai