Oreberry bush farm

I am new to computercraft and that is way i am making a topic here.

i am getting the following syntax error from my mine ing bot:
test:22: attempt to perform arithmetic__mul on nil and number

i used the following code:

http://pastebin.com/eGX6iZD8

can somebody please help me

That code won't produce that error - you're not performing multiplication on the 22nd line of your paste, and the lines where you are performing multiplication don't appear to involve nil values.

Double check that the code that you're running is the code that you think you're running.