i am using zen cart 1.3.9d
i have the product grid mod add on

my problem is with attributes, ihave searched this site high an low and none of the suggestions help me.

here is what i wish to do...

i have a product lets call is ptroduct A

product A is 20" long and the price is $10

i want to offer it as a 22" version with the price being 10% more
and i want to offer is 24: version with the price being 20% more

i have tried many different things and the prices make no sense...

please assume i am a complete dummy and give me the instructions to do this.

i am pretty sure the instructions that you give me is something i have already tried.. at this point i am assuming it might be a problem with the code.