VBA Inventory

[deadlyjack]

I'd like to generate a function for a specific cell, where the amount increases or decreases, depending on what the user types into a specific cell - connected to two different buttons.
Once clicked a button, the cellvalue needs to add/subtract from the original value, mounted in a separate spreadsheet (In this case, my manual inventory sheet). I need this function to work so that my employees can add and subtract depending on what they need.

I got a dropdown list with 10 different items, taken from my manual inventory sheet. The cell below (B8) has a VLOOKUP, =VLOOKUP(B6;Inventory!A2:B11;2;FALSE)

Kyl inventarie.xlsm
	A	B	C	D	E
1
2
3
4
5		Sort		Amount
6		Loop Mango Tango		20
7		Amount in Storage
8		60		40	minus
9				80	plus
10
11
12
Main

Cell Formulas
Range	Formula
B8	B8	=VLOOKUP(B6,Inventory!A2:B11,2,FALSE)

Cells with Data Validation
Cell	Allow	Criteria
B6	List	=Inventory!$A$2:$A$11

VBA module for plus:

Public Sub InventoryCountPlus()

i = ("B8")

Range("D9").Select
Range("D9") = Range("B8") + Range("D6")
Range("D5").Select
ActiveCell.Offset(1, 0).Select

i = i + ("B8")

End Sub

VBA module for minus:

Public Sub InventoryCountMinus()

i = ("B8")

Range("D8").Select
Range("D8") = Range("B8") - Range("D6")
Range("D5").Select
ActiveCell.Offset(1, 0).Select

i = i + ("B8")

End Sub

How do proceed or what do I need to do in order to get a functional generator, which tells the user the current amount in cell B8?

 

[deadlyjack]

Would've been easier to not have a secondparty, Inventory-sheet... But once a month I'll need to manually control the inventory & this sheet will automatically update the main-sheet.

 

[deadlyjack]

?
SOLVED: I've been running in circles...
I simply erased D9, change my VBD-code for plus, to D8 and now it works