BAPI_ACC_GL_POSTING_REV_POST not creating new document number

Dear Mr./Ms. Developer,

I created an accounting doc using BAPI_ACC_GL_POSTING_POST. The doc no. is generated by the BAPI (I entered $ as ref doc no.). Now I want to use BAPI_ACC_GL_POSTING_REV_POST to reverse the doc that I created, how do I make the BAPI generate a new doc no. based on the numbering range in the system rather than I have to enter one?

Regards,

Clarence