HI,
Normally you dfine derivation startegy, and its works at the time of transaction(Acquisiton).
Pleae check your derivations are correctly define in FMDERIVE. e.g. Create Assignment Cost Center to Fund Center assignment see below snapshot. 
Also in FMDERIVE activate the trace and post the acquisiton and analyze, why system is not deriving a fund center form cost center at the time of acquisition
No need to fill the fund center at the time of asset master, its automatically derived with reference to cost center form the asset master record. .
Regards
Javed