Limit of a function of two variables

[xxmcab]

I've tried to prove that the limit of the following function doesn't exist (I know for a fact that it doesn't exist) but I keep getting 0 as the limit with any curve I take.

lim (xy+x-y-1)/(x^2*y^2-1) as (x, y) - - > (1,-1)

 

[Dr.Peterson]

Please show your work for a couple paths, so we can see if you are making a silly mistake somewhere, or just picking the wrong paths.