infinite loop for requesting adfs/ls authrntication

We are using a AFDS/ls server for authentication for our REST services. It works fine with IE8 for request got authorixed first.
But when using SoupUI Pro, I got 401 error, Then I set Username/Password/Domain in Request Properties.
My request to our REST service forwarded to our adfs/ls server and then went on an infinite loop as below (only copied three). What was my issue?

Thanks
Bin
bin.chen@argodata.com

Fri Oct 26 10:00:28 CDT 2012:DEBUG:Attempt 366434 to execute request
Fri Oct 26 10:00:28 CDT 2012:DEBUG:Sending request: GET /adfs/ls?wa=wsignin1.0&wtrealm=https://nextgen-qa.nextgen.dev.local/&wctx=rm=0&id=passive&ru=%252fOffice%252fOfficeDataService.svc%252fOffices%253fID%253d1&wct=2012-10-26T14:49:27Z&wreply=https://nextgen-qa.nextgen.dev.local/ HTTP/1.1
Fri Oct 26 10:00:28 CDT 2012:DEBUG:Receiving response: HTTP/1.1 401 Unauthorized
Fri Oct 26 10:00:28 CDT 2012:DEBUG:Connection can be kept alive indefinitely
Fri Oct 26 10:00:28 CDT 2012:DEBUG:Target requested authentication
Fri Oct 26 10:00:28 CDT 2012:DEBUG:Authorization challenge processed
Fri Oct 26 10:00:28 CDT 2012:DEBUG:Authentication scope: NTLM <any realm>@nextgen-adfs.nextgen.dev.local:443
Fri Oct 26 10:00:28 CDT 2012:DEBUG:Attempt 366435 to execute request
Fri Oct 26 10:00:28 CDT 2012:DEBUG:Sending request: GET /adfs/ls?wa=wsignin1.0&wtrealm=https://nextgen-qa.nextgen.dev.local/&wctx=rm=0&id=passive&ru=%252fOffice%252fOfficeDataService.svc%252fOffices%253fID%253d1&wct=2012-10-26T14:49:27Z&wreply=https://nextgen-qa.nextgen.dev.local/ HTTP/1.1
Fri Oct 26 10:00:28 CDT 2012:DEBUG:Receiving response: HTTP/1.1 401 Unauthorized
Fri Oct 26 10:00:28 CDT 2012:DEBUG:Connection can be kept alive indefinitely
Fri Oct 26 10:00:28 CDT 2012:DEBUG:Target requested authentication
Fri Oct 26 10:00:28 CDT 2012:DEBUG:Authorization challenge processed
Fri Oct 26 10:00:28 CDT 2012:DEBUG:Authentication scope: NTLM <any realm>@nextgen-adfs.nextgen.dev.local:443
Fri Oct 26 10:00:28 CDT 2012:DEBUG:Attempt 366436 to execute request
Fri Oct 26 10:00:28 CDT 2012:DEBUG:Sending request: GET /adfs/ls?wa=wsignin1.0&wtrealm=https://nextgen-qa.nextgen.dev.local/&wctx=rm=0&id=passive&ru=%252fOffice%252fOfficeDataService.svc%252fOffices%253fID%253d1&wct=2012-10-26T14:49:27Z&wreply=https://nextgen-qa.nextgen.dev.local/ HTTP/1.1
Fri Oct 26 10:00:28 CDT 2012:DEBUG:Receiving response: HTTP/1.1 401 Unauthorized
Fri Oct 26 10:00:28 CDT 2012:DEBUG:Connection can be kept alive indefinitely
Fri Oct 26 10:00:28 CDT 2012:DEBUG:Target requested authentication
Fri Oct 26 10:00:28 CDT 2012:DEBUG:Authorization challenge processed
Fri Oct 26 10:00:28 CDT 2012:DEBUG:Authentication scope: NTLM <any realm>@nextgen-adfs.nextgen.dev.local:443