Error #2032 when calling a WebService operation

I'm trying to make a soap operation call. The wsdl file is loaded fine, but when I go to make a call, I get this error:

quote:

---

HTTP request error
(mx.messaging.messages::ErrorMessage)#0
body = (Object)#1
clientId = "DirectHTTPChannel0"
correlationId = "C5EF8C74-6413-12CF-7737-7E8FE675B002"
destination = ""
extendedData = (null)
faultCode = "Server.Error.Request"
faultDetail = "Error: [IOErrorEvent type="ioError" bubbles=false cancelable=false eventPhase=2 text="Error #2032: Stream Error. URL: https://foo.com/soap"]. URL: https://foo.com/soap"
faultString = "HTTP request error"
headers = (Object)#2
messageId = "55F24685-6626-C774-F58E-7E8FE6E39495"
rootCause = (flash.events::IOErrorEvent)#3
bubbles = false
cancelable = false
currentTarget = (flash.net::URLLoader)#4
bytesLoaded = 0
bytesTotal = 0
data = (null)
dataFormat = "text"
eventPhase = 2
target = (flash.net::URLLoader)#4
text = "Error #2032: Stream Error. URL: https://foo.com/soap"
type = "ioError"
timestamp = 0
timeToLive = 0

---

Here's the code for the WebService:

quote:

---

<mx:WebService id="ws" wsdl="http://foo.com/bar.wsdl" showBusyCursor="true" >
<mx:operation name="Baz">
<mx:request>
<Param>{this.keyId}</Param>
</mx:request>
</mx:operation>
</mx:WebService>

---

The swf is on the same domain (and subdomain) as the webservce, and when it isn't, I get a security error.

I read that https and webservice can have some problems when not going through a proxy, but I can't see why, and I'd rather not use a proxy; I shouldn't need one.

This happens with both Firefox and IE.