appartment number in ical

I can't work out why Ical seems to input my addresses wrongly. In my address book, I have many addresses with apparment and building numbers. The appartment number isn't coming accross into Ical when it automatically searches through the contacts and I select the address.

Eg.

Contacts:

Lindy's home

345/6 Edward Street

Ical shows:

Lindy's home

6 Edward Street

Any ideas how to get the appartment number showing up?