FRInvestment properties transfer question

Hi, I tried the search function, but didn't find anything that answers my question. Could you help with my understanding of revaluation of a property asset please that has been transferred to investment property? My understanding is I can use F.V. revaluation under IAS 16 to account for the revalued asset. E.g. originally, property worth $15k with a useful life of 15 years, depreciated after 2 years to $13k, but at end of year 2, revalued to $20k. Therefore asset debited by $7k in SOFP, credit against depreciation charge in income statement of $2k and remaining $5k is credited in revaluation surplus in O.C.I. However, my study text gives me the following example: Cost of property (used as HQ for business) $250k in 1/1/X0 with 50 years U.E.L. Change in use @ 30/6/X9 - transfer to investment property F.V. @ 31/12/X9 is $350k Therefore: Cost: $250k Dep'n: ($47.5k) [9.5yrs * $250k] Carry amt: $202.5k as at 30/6/X9 Reval: $147.5k F.V.: $350k as at 31/12/X9 Why does the full amount of $147.5k go to the revaluation surplus and not $47.5 against the depreciation charge and $100k to the revaluation surplus? What have I missed? Many thanks.