In mass billing documents creation, some of them do not created/generated FI document

Hi,

When I create severals billing documents thru VF04, some of them do not generate the accounting document given me the following message:

Error message:

Document 90080752 saved (no accounting document generated)

Message no. VF050

If I look in VFX3 the Notes (Shift`+ F5), I have the message of "Error Log". Also, in the "Incomplete due to" column, error message is :

Error message:

FI/CO Interface

Then if I release the document with VF02, the accounting document gets generated. Why????

I am sure of:

· The Account Determination Analysis is correct.

· The Billing document type is not "blocked for transfer to accounting", with out the flag in posting block.

Thanks in advance!!!

JCR