[pdftex] Relative link with URI

[Yann Blanchard]

Hello
I'm sorry if my problem is simple , when I write this file :
******************************************************************
\pdfstartlink
attr{/Border [0 0 0]}
user{
/Subtype /Link
/A <<
/Type /Action
/S /URI
/URI (http://www.tug.org/)
 >>}
\Red \bf \footnotesize http://www.tug.org \Black
  \pdfendlink}
**********************************************************************
J have this error  message  from Acrobat link : "Cannot follow this 
relative link ..........", I  have read the PDF Manual but I have not 
understood , thanks for help .
Yann Blanchard