ports/devel/automake-wrapper: ln: /usr/local/bin/aclocal: File exists

I get permanently this error when doing portmaster -dvf lighttpd.

It is essentiel having build everything along the lighttpd server due to 
a /usr/local/lib corruption. ports/devl/autotools are already installed. 
Now I get stuck in this nasty error shown below, I can not circumvent. 
How to simply force the installation?

Please respond to my email address also since I'm not member of the 
ports-list.

Thanks in advance,

Oliver

===>  Installing for automake-wrapper-20071109
===>   Generating temporary packing list
ln: /usr/local/bin/aclocal: File exists
*** Error code 1

Stop in /usr/ports/devel/automake-wrapper.