Double declining method

Hi..

we're using BPcs v.6.1.01 client server
and right now i still can't use the double declining method for an asset
depreciation, like how to set up the depreciation method and the right
calculation, right now i have been trying to define the depreciation method
but the result that i got only half of the right caculation, or might be
there was a different name that i don't recognise.

for an example :

i got an acquisition value 500
asset life 4 years
salvage amount is 0
and the basic calculation :

[ 100 % / 4 ] * 2 = 50 %

first year depreciation should be
500 * 50 % = 250

## but the amount that i got was only  125 *wondering why was that happened
too.. :(

second year depreciation should be
[500-250] * 50 % = 125

## i still can't process it because i got a problem with thw 2002 period
master set up.. there is a message " Invalid Fiscal Date " -->> can we
process the next future depreciation to find out that the calculatuin was
right till the end of assets life.

third year depreciation should be
[500-250-125] * 50 % = 62.5 rounded to 63

fourth year depreciation should be
[500-250-125-63] * 50 % = 31.25 rounded to 62.5 because salvage amount is 0


thank's in advance for information that can be shared to me.. :)