It sounds like you might be using the Juicebox Module for Drupal (and that the problem might be directly related to the Module and Drupal, rather than with Juicebox itself. (It sounds like you are trying to display certain images from within your Drupal site and this image data needs to be gathered by the module's code before the being passed onto Juicebox for display).

Please note that the Juicebox Module for Drupal is an unofficial plugin which was not written by ourselves.
As such, I would recommend that you post your query in the Drupal forum where the author of the module (Ryan Jacobs) should be able to help you further.
He is active and very helpful in the Drupal forum and has a much better knowledge that I have of both the module and Drupal.

Incidentally, an alternative to using the module would be to create a gallery first on your computer using JuiceboxBuilder-Pro and then embed the gallery into your Drupal page using the baseUrl method of embedding following the Embedding in a Drupal Site instructions.

I hope these notes point you in the right direction.