Invalid Module: #template-wrapper > table:nth-child(7)

Without seeing the full email template, this is going to be hard to diagnose, but I wanted to at least offer a bit of guidance. Some things you can look at to help deduce what might be the problem include:

• Do extensive tag closure checks. The most common reason a module will fail is that it isn't properly closed in some way with a stray missing </td> tag or what have you. You can use an HTML linter for this, but a site like HTML Tidy Online or Closing Tag Checker can work in a pinch.

• Ensure your module setup works with your container setup. Every module must be within your .mktoContainer parent and all of your module children must be at the same hierarchy level—so if your container is a <table>, the modules all must be immediate <td> children; if your container is a <td>, they all should be <table> children, and so on.

• Try pulling your modules one-by-one from your code to see where there may be issues, then re-introduce them once they've been known to work.