GL budget balances are negative, how do I fix that ?

client is using Encumbrance accouting.

I don't think the  Year-end carry forward balances was run at end of Dec 12.  We are now in APr -13 period, some of the budget balances are negative.  I think this is because none of the year-end balances were caried forward and when they matched the spend (on Purchase Orders) for jan, feb and march periods in 2013, the balances became negative.

Does anyone know how to resolve this ?   i.e. so that the balances are postive amounts as they should be