Credit on Account

Hi,

In our current setup we can put positive transactions onto customer accounts but not negative ones, we would like the option to put negative transactions (i.e. credit notes onto customer accounts but I don't know how to set this up. I guess a good example would be when applying a receipt then it will not let the unapplied amount become a negative figure. Any help with this would be greatly appreciated and we're using Oracle 11.5.10.2.

Thanks,

Allan