Outsystems App inside Iframe - Can't login using IE

I need to call an outsystems app from an iframe.

I created a local html file and user the outsystems app as source.

If I login in Chrome everything goes fine. If I am in IE the login is not successful. It executes the login action, in debug I see that the result of the login is ok but when it redirects to the homepage it shows me the login page again.

When I try to login whit invalid username/password the feedback message ha written "An exception occurred in the client script.
Error: Permissão negada " instead of "Username/Password invalid"
Using P3P: CP="NOI ADM DEV COM NAV OUR STP" in header works.
Thanks João.
An update, the error message in feedback message, when introducing invalid username/password, continues to appear as:

An exception occurred in the client script.
Error: Permissão negada 

Do NOT just set the P3P header to that value because it works. It is a *legally binding contract with your end user*.

Do this right. Go to P3PWiz or get a copy of the old IBM Alphaworks P3P editor and write an *accurate* P3P policy, and use THAT header.

Setting an inaccurate P3P header opens you to legal action and it is unthical.

Used it only for testing purposes because it didn't worked in my computer. When tested in other computers it worked fine, so I didn't had the need to write e P3P policy.