How to create the logic in the import scenario to get the Sales Price from the sysem when it is not available in the excel file.

Hi,

I tried to create an import scenario for the Sales Order Bulk update. Here in the Sales Orders there are some items that price need to be taken from the Sales prices setup system and there are some items that price need to be taken from the Excel. When uploading Sales Orders through the import scenario I tried to write the Logic in the import scenario as =IsNull( [Unit Price],[Transactions.CuryUnitPrice]), But the system does not take the price when creating the Sales Order if the unit price is not avaialble in the excel file. How can I solve this?

Thanks in advance.