Make my first assertion work

Just started to play with SoapUI (4.5.1 non Pro) to see how it could help us, and follow this video:
http://www.youtube.com/watch?feature=pl ... PbAy_oAINA

I can't make any assertion work, neither giving all <allregionlist> or true/false,
I used mobilefish for testing.

declare namespace SOAP-ENV='http://schemas.xmlsoap.org/soap/envelope/';
exists(//SOAP=ENV:Body)
....
true

Nothing asserts OK, appreciate your help what could be wrong?
Tx
Dai