login credentials work manually, but not via api?

Our software has a webex integration which permits the creation of meetings via the xml service.  We are able to create meetings successfully from a range of our sites to various customer webex installations, but we're having trouble with a new one.

This customer has given us login credentials which work beautifully if we log manually into their webex site, but these same credentials are refused when we try via the software.

Is it possible that there is some switch that has to be flipped on the webex side to enable automatic logins via the api?  Our customer's IT staff is new to this process as well, and we are not sure how to guide them.  With every other install we have it's simply been a matter of obtaining the relevant credentials!

Hello,

     API will allow logon without any additional setting. Special characters may need to be encoded, if any exist in the password. You should also verify the site id and partner id values actually match the site you are trying to use, if using XML API.