There are a couple of possibilities here:
1) The barcode is unscannable.
2) The barcode scanner is not reading the code.
So the first thing you need to do is find out which.
Scan a known-good code - preferably a Code 39 (normal name for 3 of 9 barcodes), but start with one from a packet of peas if you have to. Does the scanner read it?
If it does, then find a Code 39 barcode and scan that. The Wiki page has a couple:
http://en.wikipedia.org/wiki/Code_39[
^] - though the quiet zones do look a little thin on the second example.
Does that read?
If it does, then you have a problem with your code - and you need to look at the documentation. Try printing the same Code 39 as you got from Wiki - can you see anything obviously different?
If it doesn't, then check your scanner - it may be setup not to read Code 39 (some are set to read only specific code types - ITF for example, or Traded Unit codes only perhaps). See your scanner documentation.
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