Fixed Asset Impairment was entered. Later market conditions mean the asset value needs to be incre

An Asset was impaired as its market value had decreased.   

2 years later the market conditions have changed and the asset's recoverable value has increased and so we want to enter a negative impairment to bring the NBV in line with the recoverable cost.

If the NBV at the time is higher than the amount of negative impairment we want to enter then this works.

IE    NBV is 200

We enter a negative impairment for -100  < seems Ok and NBV is now 300

However if the NBV is lower than the value of the negative impairment we get this error:

'Impairment cannot be charged for asset xxxxxx as the NBV after considering current month depreciation is either zero or less than impairment loss.'