ULR iview with dynamic parameter

Hi to all,
I read a lot of post on this theme but I don't to make what I want.

I have this BEx web template URL:
http://hostname:port/irj/servlet/prt/portal/prtroot/pcd!3aportal_content!2fcom.sap.pct!2fplatform_add_ons!2fcom.sap.ip.bi!2fiViews!2fcom.sap.ip.bi.bex?TEMPLATE=ZUWT_TEST_120315&BI_COMMAND_1-BI_COMMAND_TYPE=SET_VARIABLES_STATE&BI_COMMAND_1-VARIABLE_VALUES-VARIABLE_VALUE_1-VARIABLE_TYPE=VARIABLE_INPUT_STRING&BI_COMMAND_1-VARIABLE_VALUES-VARIABLE_VALUE_1-VARIABLE_TYPE-VARIABLE_INPUT_STRING=001.2012&BI_COMMAND_1-VARIABLE_VALUES-VARIABLE_VALUE_1-VARIABLE=FISCOBB&BI_COMMAND_2-BI_COMMAND_TYPE=EXPORT&BI_COMMAND_2-EXPORT_FORMAT=XLS
and I created a URL iView to open this from external site.

I define all values into URL iView and this works fine with this URL:
http://hostname:port/irj/portal?NavigationTarget=ROLES://portal_content/iViews/Embed_iView&NavMode=3&j_user=user&j_password=password

Now I want to make dynamic the parameter BI_COMMAND_1-VARIABLE_VALUES-VARIABLE_VALUE_1-VARIABLE_TYPE-VARIABLE_INPUT_STRING to pass the period of my interest.

On help portal it's described to use this configuration:
URL parameter: BI_COMMAND_1-VARIABLE_VALUES-VARIABLE_VALUE_1-VARIABLE_TYPE-VARIABLE_INPUT_STRING;
Value: null
Type: String
Personalize: Read/Write
Name: PERIOD;
but after this configuration the ULR
http://hostname:port/irj/portal?NavigationTarget=ROLES://portal_content/iViews/Embed_iView&NavMode=3&j_user=user&j_password=password&PERIOD=001.2012
doesn't work.

How do I have to make the correct configuration?

Thanks in advance,
Giampaolo