SOAP is my least favorite server side web service to hook into. It can be one unforgiving SOB... I've spent countless hours trying to bend and break code to get it to interact with different soap variations. Seems like every company has their own namespace and naming convention to follow and many times these conventions are not labeled or easily found. Tech support for one of these lovely companies recently pointed me to an outstanding piece of open source: soapUI.
Open it up, drop in the URL to the WSDL and it will immediately show you all the Operations that are available. You can then explore any operation and view the variables and structure of the XML that the Operation is expecting. It will even let you enter in variables and hit submit to see what kind of response you will get. This is 100x easier than trying to figure out why the call failed via logs and Flash stack traces... which usually just say streaming error or something else equally generic.
On a side note... anyone have a better tool than wellconsidered as for as AS3 Soap methods go? I greatly appreciate Pieter Michels efforts, they helped me immensely during my first SOAP excursion. However, the more I use it the more I realize how it is unfinished and lacking key functionality. We are considering trying to create a Flex swf just for the SOAP methods and load it into our Flash project next time... but seems like there should be an easier way.