can't get URL link to work

Every time I try to link part of my text to a URL, the editor truncates some of the address...rendering my link dead. For example:

I choose http:// then enter the URL: www.abfsport.nl/abf-international-sport ... football37

when I check the link on my site it comes up without the www.

I've also tried using "Other" instead of http:// and it duplicates the www.abfsport.nl

Any suggestions? Thansk!