Hello KF
Your Icon Creator must be able to create a *.ico file which contains a 32x32 AND a 16x16 Icon. If you create "only" a 32x32 Icon, then you'll get this error. The 32x32 icon is used for the "desktop view" and the 16x16 is used in the title bar of your executable.
Please review the KB linked below for more informations:
http://digital.ni.com/public.nsf/websearch/528734296689555B862565F5007C6181?OpenDocument
Hope this help.
Luca
Regards,
Luca