Loadrunner 11.52 and SAP BI, bttoken capture problems

Hi

I am trying to test a SAP BI application.  When I record, I see that it receives a token called bttoken during the login process. This is then used in calls after login. When I let LR correlate this, it creates this code

web_reg_save_param_regexp(
"ParamName=CorrelationParameter",
"RegExp=bttoken=(.*?)\";\\\n</script",
SEARCH_FILTERS,
"Scope=all",
"IgnoreRedirections=No",
LAST);

web_submit_data("logon.faces_2",
"Action=http://server:port/BOE/portal/number/InfoView/logon.faces",
"Method=POST",
"TargetFrame=servletBridgeIframe",
"RecContentType=text/html",
"Referer=http://server:port/BOE/portal/number/InfoView/logon.faces",
"Snapshot=t3.inf",
"Mode=HTML",
ITEMDATA,
"Name=_id0:logon:CMS", "Value={strEnvironment}", ENDITEM,
"Name=_id0:logon:USERNAME", "Value={strUser}", ENDITEM,
"Name=_id0:logon:PASSWORD", "Value={strPassword}", ENDITEM,
"Name=com.sun.faces.VIEW", "Value=_id147:_id148", ENDITEM,
"Name=_id0", "Value=_id0", ENDITEM,
LAST);

Note, that

{strEnvironment} = server:port.

WWhen I rerun this, the value for bttoken is not found. If I try to catch it with a web_reg_save_param_ex construction, it is also not found. Who has experience with this problem and can set me on the right way? It looks like the bttoken is somehow not returned, maybe the value in

"Name=com.sun.faces.VIEW", "Value=_id147:_id148", ENDITEM, 

is wrong, cause this is different in every recording, but I do not know the mechhanism beind this.