Embedding a form on SSL secure site- iframe element isn't secure

Embedding a form on SSL secure site- iframe element isn't secure

When I embed a form in an iframe on my site-  with external SSL certificate,  on some Internet Explorer machines it indicates that some elements on the page are not secure-  the element they are referring to is the iframe with the embedded form.

My hosting service tech and I went through all the html code we could find, looking for references inside the form that referred to the unsecure (http:) site so we could manually change them to https:   -but that didn't work.

Any ideas on how to make an embedded form secure when it is placed on a SSL secured page?

Thanks for the help-