sometimes i got samples up on the step sequencer and i can't play them higher or lower on the piano roll, any key i hit just makes the same flat sound without changing the pitch. is there a reason for this?
It's probably because they were automatically stretched somehow...
To disable time stretching for a sample, turn the Time knob maximum left (set to 0). This is the default mode when samples are dropped on the Playlist.
Also, if that annoys you... make sure that, in the General Settings (press F10) , 'Read sample tempo information' option is OFF (in the Advanced section of the window)