Difference in DB Depreciation answers

[Carsen]

The HP Prime gives a different answer for following declining-balance depreciation problem when compared to the HP-12C. The problem is on page 141 of the HP-12C user's guide, except I'm using a factor of 200% instead of 150% . Here are the problem's variables...

Cost = $50,000
Salvage = $8,000
Useful Life = 6 years
Factor = 200%
First Used in the beginning of September.

The Prime and 12C give similar answers for depreciation and the remaining depreciation for years 1, 2, 3, & 4. Years 5 and 6 are when the answers are way off. This is the answers each calculator provides for the depreciation for that year.

Year 5:
12C=4,389.57
Prime=3,917.70

Year 6:
12C=779.15
Prime=1,251.03

My Prime has the latest firmware and I have checked what I have entered into my calculators more than twice. I even re-entered my partial year declining-balance depreciation program into my 12C. I always doubt the user before I begin to suspect the calculator. So this means there is no input error. What do you all think is going on?