Error: Special G/L indicator not defined or incorrect

Hi,

Iam trying to park a document using FBV1.

Posting Key: 19 (Special G/L credit)

Account: Customer Account

I get an error, "Special G/L indicator not defined or incorrect". It says in the procedure,

"Maintain the entry for account type "D" and special G/L transaction "" using the FI customizing functions".

Please advise where i can do the configurations for the same.

Thanks,

Safi