URL appears without correct punctuation in some output styles

I have electronic citations, with the URL in the ‘Source’ field. In some output styles, the URL has no full stops. For example, I need American Medical Assocation output style for my article. The URL looks like this:

 http://www hpa org uk/web/HPAweb&HPAwebStandard/HPAweb_C/1203348026613

This is not useful, because the link doesn’t work and a reader will not know what is wrong with the URL.

I know it is correctly entered in the record, because when I use another output style (e.g. American Journal of Preventive Medicine) it appears correctly:


Please can anyone help?