Loading one external SWF into another SWF across domains

I have a.swf, which is the SWF file for my main application, and it's trying to load in b.swf, which contains some additional resources as well as some Actionscript. a.swf lives on sub1.domain.com and b.swf lives on sub2.domain.com (both on the same domain, just different subdomains.) In a.swf, I've loaded the crossdomain.xml from domain.com and also added the following code into both a.swf and b.swf:

Security.allowDomain("*");
Security.allowInsecureDomain("*");
开发者_C百科

Do I need to load the crossdomain.xml in b.swf as well to prevent a security error or is having allowDomain/allowInsecureDomain enough?

Further info: - Using Flash Player 9 - Using AS3

Yes, you need sub2/SWF B to load the crossdomain more so than the sub1/SWF A.

Quick question though... are they same domain and different third levels?