I'm, wondering if this would work??  

1) I get a mortgage for $300K at a 3% rate (a bit high for the current rates here in Canada)

2) I use the $300K to invest in a low fee fund: http://www.morningstar.com/funds/XNAS/VTSMX/quote.html

3) I use the interest to pay the mortgage fees, and continue to invest the rest of the returns. 

This looks like it could work - am I missing anything?

Thanks!