I second everything that Barls says (except the profanity!).
I had a look on the
Black Rock site and it doesn't mention that the yeast with the kit is a lager, so in the absence of any evidence to the contrary I would assume it's an ale yeast, which is what comes with most "lager" kits.
Therefore, it was a good idea to buy a lager yeast to ferment it with. What sort did you buy?
As an aside, the Black Rock site also says to, during fermentation, "keep the brew between 18-28degC". DO NOT DO THIS! You will end up with shocking beer if you ferment it at the top of that range, regardless of whether you use an ale or a lager yeast.
Note that activity in the air lock is not a reliable way to know whether the brew is fermenting. Check out "
Common question: My brew is not fermenting".
Hope this helps. Let us know if you have any further questions.
Cheers,
Oliver