Samantha,
The option in "Calc. Plan.." is to respect the Planning Parameters when you fall below your Safety Stock level. Meaning if I have an Order Multiple of 6 and I am two units below my Safety Stock Level, the system will order in multiples of 6. If I was NOT using the option to respect, the system would have ordered the two units to bring my Safety Stock back, then ordered again for any remaining demand.
When you say it is not working what results are you expecting, and what results are you getting?