import not assigning key field

Greetings from a first-timer

First of all I would like to give congrats to the developers as they have done a great job with this product. I have been able to accomplish the majority of my project without the need of support until now. The business need I am addressing to basically an order entry system containing and order header and order line item. The line item file is related to the header by the order number and a line number ( one-to-many relationship). The order number in the header is assigned by serial#.

The task I am having the problem with is the need to duplicate an order (both header and line items). The way I am doing this is with a script that:

- accessing the order entry layout

- exports the order line items to a tab-delimited file

- duplicates the header record (with a newly assigned order number)

- ... data manipulation with dates

- import the line items. The order number is not imported according to the mapping.

The import does not assign the order number to the line item, all other info is correct. The line item order number is null.

I have tried various thing like making the line item order number a calculated value of the order number and a lookup value. No impact on the order number.

Any thoughts ... I feels as though I am re-inventing the wheel at great cost, so if there is a better way to accomplish this task I am willing to change my method, as every thing else works fine...

Thanks for your consideration.