invoice is incomplete due to export data

dear all

my invoice is incomplete due to export data

so i could not generate the accounting data for the invoice can any one suggest me wat will be the solution and wat i ve to fill in export data...

the following are the error comming in eaach step

<b>Document 90000003 has been saved (foreign trade data incomplete)

Message no. VF072

Diagnosis

The billing document you have edited contains foreign trade data. These are however not complete.

This means that the document cannot be transferred to accounting (FI).

System Response

The system issues a message.

Procedure

Maintain the incomplete foreign trade data. Then you can transfer the billing document to accounting (FI).</b>

please suggest me the way

with regards

subrat