Making a custom function available in any Excel Sheet (Personal.xlsb) for Excel 2010

Hi There,

I have a function (which is a Barcode generator) which I want to be available in any spreadsheet, simply by typing in the formula,

= Code128(cellref)

(where 'cellref' would be "A1" for example - the cell which contains the number that is to be converted into a barcode)

I was under the impression that the way to do this was to place the module in the hidden "personal.xlsb" sheet and then it should be available in all sheets. This doesn't appear to work.

I also read somewhere that when referring to a function located on the 'Personal' sheet that you must add "personal.xlsb!" before the function page, but either I'm not doing something right (very possible) or this doesn't work...

= "personal.xlsb!"Code128(cellref)

Can someone please shed a little light as to what I'm doing wrong? Is there an alternative way to achieving my goal? After I get this working on my PC, I will be adding it to a couple of other colleagues' PCs so that they have this function available to them too.

(Using Excel 2010 on Windows 7)