Hi Sandeep,
First check whether you have activated funds management. If the Fund value is blank in table V_FM01_BLANK, then error F6804 will be trigerred.
Trace on FMDERIVE (note 666322) to see if "Fund" is derivated properly.
Please turn the trace ON to verify the correct FM account assignment derivation with this scenario, "Fund" by steps defined.
Basically, even when FM and FI are not updated, FM calls the FM account assignment determination/derivation (FMDERIVE) and then verifies the values derived against the customizing, in this case, the fund is a required field. The reason is that applications other than FM/FI can use
the FM objects derived such as commitment item, funds center, and fund.
regards
Waman