errorCode: 400, message: "Subscriber '...' is not valid"

Hi There!

i'm running into problems, and hoping the community can help me. because of the structure of my page, I can't just use the embed code given to me by marketo.

The code, as i see it, can ben broken into 3 parts:

1. include forms2.js
2. insert the form (with the correct form name) into the dom
3. load the form from marketo, making sure the form id specified in the load command matches the id on the form.

1. since my environment is wordpress, i'm enqueueing the forms2.js script - it is in the header
2. i'm inserting the form - with display:hidden on it as the first element in the page (<form id="mktoForm_67"></form>
3. AFTER both of those happen (i.e., the form tag is IN the dom, and the script IS included), i call the load command:
MktoForms2.loadForm("//app-sjst.marketo.com","...", 67);

when the load command hits, i get the following error:
Error loading form: Object {error: true, errorCode: 400, message: "Subscriber '...' is not valid"}

i've commented out the marketo ID, but it DOES match the munchkin id i have on the page (in the footer, below everything else).

I tested the embed code - in a test page - and it works just fine, but, i'm not sure why i would get this message, if my logic above is correct?

Please help?!