The "Nokia 6021" is not compatible with iSync:
http://www.apple.com/macosx/features/isync/devices.html
Best to check the compatibility of a product before assuming it will work with your operating system. There may be hacks out there to make the 6021 work with iSync (I know there are hacks for certain unsupported Motorola phones), but I cannot find any hacks specific to the 6021 to get it to work with iSync.