I have a swf hosted at domain A, and I have a html at domain B

My swf is able to be loaded from accessing the html at domain B. However, the swf gets a SecurityError: Error #2060: Security sandbox violation: ExternalInterface caller http://domainA.com/TrialApp.swf cannot access http://DomainB.com/.

The as3 is just the below:

ExternalInterface.call("javascript:_invite();");

I've also loaded the crossdomain policy file from Domain B during initialization.

Security.loadPolicyFile( "http://DomainB/crossdomain.xml" );

How do I go about solving this?

in my html, I have

allowscriptaccess='always'

Thanks in Advance