Conversion Factors from Object Dependencies in batch management

hi all,

i have create following dependency to calculate weight of a plate

000010 $self.plate_weight1 = $self.plate_width1*$self.plate_length1*

000020 $self.plate_thickness1*$self.steel_density/1000000

but i am not seeing any auto calculation after putting values in respective characteristic.

i have a class BATCHUOM_OD1 with following characteristics

PLATE_WIDTH1

PLATE_LENGTH1

STEEL_DENSITY1

PLATE_THICKNESS1

PLATE_WEIGHT1

I have put dependency for plate_weight1 as per above

please advise where i am wrong.