This has happened to people before (though I think only XP or Vista users)... go into LW's options, disable adding to iTunes. Remember to click 'ok' on the iTunes config page & also again on the main options page.
Restart LW. Now open LW & go back into options, enable adding to iTunes & then once again restart LW.

I know it's a pain, but seems that disabling > re-enabling those iTunes options is often a fix.

If that doesn't help, let us know which version of LW you're using & also which version of iTunes