Abstract
As user of a custom theme you should know that the extensions are developed to work with the default theme of OpenCart, the reason it’s clear, there are more than 2.000 custom themes only in the official market, as you imagine, there is no way to make the extension compatible with all of them.

OpenCart extension’s system is based on mod patching, so, if your custom theme or other extension has modified the standard code, it’s possible that some important lines have changed, if those lines are just the ones used as entry point for a given extension, it will be fail.

Many of our customers have adapted our extensions to work with their custom themes, so it’s possible, sometimes easy, sometimes could be more complex.

Anyway we are going to try to help you, as we helped other customers to adapt the extension to their own installation of OpenCart, please take in consideration that this work is out of our responsability.

Take a look at logs
First you need is to take a look at any log file you will find in Extensions & Modifications tab, in OpenCart admin zone.
These logs will show you where is failing each extension.

Sometimes it’s as simple as this example
In OpenCart standard code, a line in product.tpl says:

... id="cart"...

In your custom theme code, same line in product.tpl maybe says:

... id="super_cart"...

If the extension looks for “cart” will not find it, so you can change in the xml file of the extension and make it look for “super_cart”…

Lost? Ask us for Custom Theme adaptation