Not allow a number repeated

We have an order form that we use for our clients, and their billing requires a unique VON number for each Manufacturer order.  The form is constantly changing, and I have used Named Ranges such as "VON_Almark", "VON_DavdisonsEggs", ETC.   What is the "softest code possible" that will look at all VON cells and make sure they do the following:

1) Has to be 10 digits
2) Only has to have a VON if the Cost is completed (named ranges of COST_ManufacturerName)
3) Cannot reuse a VON number on the form.

Thanks! Form Screenshot
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can you post a sample worksheet so we can cater a solution for you as several elements that need to be concidered
1) do you have several worksheets in the same workbook to verify ?
2) you mention named range "VON_Almark", "VON_DavdisonsEggs", ETC. How to look for ETC if we dont have the names makes it a bit more complex !
3) Presume the VON number you are refering to is in the yellow cell but the picture fail to give us the column is it B?

ETC ...
sharpapproachAuthor Commented:
Here is my test form.  Thanks!
Hi again
Is this what your looking for ?
Pls try this file and enable macros and see the cursor now in B69 it has a similar value elswhere try changing it and see the result look for the couple of row before this one oyu will see the value change this one to be same as the new one below and see results is this what your looking for ???

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Microsoft Excel

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