Can't get bike into lowest gears

[aaronp18]

I bought a MTB cassette 11-34 and installed it with no problems but I can't get into the lowest 2 gears. The chain seems to get stuck and I have to shift back a couple gears to be able to pedal.
There was a road cassette and I put on a MTB, could that be the problem?
How can I get the derailer to get the chain onto the lowest two gears?
Thanks in advance.

[Alex Ramon]

I answered your same question over on the <a href="http://bikeride.com/adjust-rear-derailleur/">rear derailleur</a> comments. Watch that video at about 2:25 for tips on adjusting the 'L' screw... it sounds like it might be too tight.