There are two scenarios here.
1) create two different screen banks and jump between the two or
B) The trick I use

- Copy from
copy start(bank_a)+32 to start(bank_a)+64 into Start(Bank b)
logic=bank b
I hope this kind of makes sense...
Also, if the bank contains palette data are you jumping 34 bytes for this?
If you're using multiple pictures might I suggest using the filebank system in The Missing Link?
Then its simply a call to the correct file WITHIN the filebank... check the docs out. Its a pain and takes some working out but once you've cracked it you can create huge files with 600k of files within and simply get file (a) or get file(b)
Oh, and as a last note... if its feasible, build your scroller into 16x16 sprites, and use the mapping system in The Missing Link - The "BLACK" demo uses this technique