Here it is, personally witnessed enough times now that I have promoted it from simple theory to law:
If you order something to be delivered to your house on your work-at-home day, it will be delivered a day late, you will be at work, and you will get stuck in the loop of multiple delivery attempts. The carrier will max out on re-delivery attempts before your next work-at-home day, and you will be hauling yourself down to a distribution center on the edge of town to pick up your package. If you order something to be delivered to your workplace on a day you will be there, it will be delivered to your workplace on your work-at-home day.
(I’m working in Berkeley today and the big monitor I ordered to make myself more productive is sitting at Yahoo! HQ, delivered a day earlier than expected. Sigh.)
Chad Dickerson's blog 
I actually changed the mailing address on one of my credit cards to my work address. That way it’s easy to get *everything* shipped to work. Even if i’m not at the office, our shipping dept is.
Your law matches my experience though.
Exactly! The next thing we need to figure out is who tells these shipping people where we are.
But, in all seriousness, i wonder why the shipping companies can’t solve this problem. Like, They have all these UPS stores and fed-ex stores at every corner. Why not just give you a choice of nearby locations to pick up from. If you are not home, drop it off in the nearest fedex or ups store.
I simply wish I had the opportunity to work at home so I can give this theory a try .
I also can provide evidence to support this law. On numerous occasions I have done just as you describe and missed deliveries. I would extend the law to state that if you work from home to wait on someone to perform some service, whether that be work on the home or otherwise you can also expect that something will come up and they will need to reschedule.
And as for the large monitor – I have one of those Dell’s at the office – maybe I need one home too.