Hi Masa,
I have created the transport requests.After that, the link: http://help.sap.com/saphelp_uiaddon10/helpdata/en/21/211535923c46d88a14e8a1a048fde1/content.htm
states to open the launchpad designer with scope as conf/cust and click settings button to assign workbench request and package. In my case on clicking the settings button i get the same error dialog which is shown above.
Thanks,
Srikanth M