Excel Average If for two different sheets

[NDMDRB]

Hello,

I have a workbook with two sheets, "Items" & "Purchases"

I have two userforms also, "frmNewItem" & "frmPurchases"

In "frmNewItem" I have several textboxes to add the item details to sheet "Items" (one of these boxes is "OpenCost" that added in column "K")

In "frmPurchases" I have several textboxes also to add the purchase invoices to sheet "Purchases" (In column "E" is the cost of these purchases)

In sheet "Items" Column "D" (ex: "D5") I have this formula that get the average cost from sheet "Purchases" of each item...
=IFERROR(AVERAGEIF(Purchase_Barcode,A5,Purchase_Cost),"0")

What I'm looking for is to get the average cost from sheet "Purchases" (As the formula above) and the open "OpenCost" from sheet "Items" column "K5"

Any thoughts!!