Out put is not triggered during Billing as per Access Sequence

Experts,

I am working on Email output to Billing.

For that,

1)I have created new Z table, 903 with the combination of Sales Org/Billing Type/Standard Communication Strategy .

2) Created one Z access sequence, Z002  with First access as 903 table  and the second access as 11 - Sales Org-Billing Type combination(This is a std. table)

3) Assigned this access sequence to the new output type: z002.

4) I have maintained the relevant condition records, for the 903 combination----> Email output and 11 combination---> Printout option.

So as per the access sequence, when I am creating the billing document, system should trigger the email output first (If it matches the requirement) and  Printout option if it does not matches the first option.

Now I am creating a Billing Document and the system by default triggering the Print out put.It is not triggering the  Email output.

The strange point here is , if I am displaying the document it is showing as Printout Output and if I am going to the change mode, ie) VF02----> The system re triggers the Email Out put., which is a correct one.

Experts, Anybody come across issue like this? Pl. throw some light on this.

Regards

Srinivasan