Designtable to Custom properties

I have Solidworks 2014.

Auto-link a custom property field to a cell in design table and make it auto update on a dimensional change in model space.

Here is what I am trying to say.

If I have a part made A1234 out of Flatbar, for example 0.25" Thick x 3" Width L=200mm is A1234 raw material. I want to have a custom property field called materialpartnumber that automatically updates itself based on thickness & width. (length does not matter since I buy a 20' stick and cut to length).

This is what I tried which fails to auto create.

I created a designtable with my thickness & width dimension.

I created a VLOOKUP table, designating each inch dimension to a numerical designator as shown below as an example

0.25     1

0.50     2

1.00     3

3.00     4

I then linked a custom property field to design table $PRP@materialpartnumber

now I used vlookup function and basically built the material partnumber, in this instance to be 14

problem is if I change either of dimensions (lets say to 0.50 x 1.00) the materialpartnumber does not reflect the new part number that it is supposed to be which is 23, it still shows 14.

Only way I get to do it is to reopen the design table and close it, if I do this the materialpartnumber shows the correct partnumber.

Now I can write a macro to update the table every time user wants to assign other properties to the part, but I do not want to do this if I can get away with self update.

Do not want to create configuration specific material part numbers either, that just makes my template huge and an assembly even larger

Any help in this matter will be of great help.

Ashok Anumula