Depreciation Calculation at Retirement

Hello,

Trying to figure out what my system is doing.  Here's my Asset settling.

Cost $10,000

DPIS Jan 2010

Method: MACRS DDB , 3 Years and Half Year Prorate Convention

Asset Retired March 2012

Rate Computes to"

Year 1  .33333         2010

Year 2  .44445         2011

Year 3  .14818         2012

Year 4  .07407         2013

How much year-to-date depreciation should calculate on the asset?  I think ($10,000 * .14818 = $1,481.80) / 2 (1/2 years worth) = $740.90, but system is doing something else.  Also, years 2010 and 2011 calculated depreciation according to the rate chart correctly.  Any help would be GREATLY appreciated.