Problem with calculation field

[renev]

Please help me to correct the calculated fields.

Brief summary of my problem.

We import part numbers from external system to manage BOMs.

First scenario:

We import all part number information from extenal system 1.

I have standard price and current price columns in my filemaker database wherein standard price is fixed for a part and current price is keeps on changing. For the first time when a part number is imported current price will be same as standard price. so I created stored a calculation field

CurrentCost = If ( Current Cost ≠ 0; Current Cost;Standard Cost)

Next time when that part is imported current cost should not get changed.

Next sceario:

We import BOMs from some other system where we get information for all the parts except price information. Price information I have to get from the master database.

I created a unstored calculation field to pick the price from parts table.

Unfortunately price is not getting displayed in my BOM List.

Could anyone please help?

[renev]

Please check copy of my database for better understanding of my problem.

BOM_Database.zip