pbuild fails with "Permission denied"

[Ole Streicher]

Hi,

I am quite new to pbuilder, and could already successfully build two
packages. Howeverm my third package fails within the build process:

[...]
make[2]: Leaving directory `/build/buildd/libwcs-4.4.4/utils'
/usr/bin/install -c -m 644 C/libwcs-4.4.4.a /usr/lib
/usr/bin/install: cannot create regular file `/usr/lib/libwcs-4.4.4.a': Permission denied
make[1]: *** [install] Error 1

The full log is available at
http://launchpadlibrarian.net/48532874/buildlog_ubuntu-lucid-amd64.libwcs_4.4.4-1_FAILEDTOBUILD.txt.gz

When building directly, everything works fine.

When I put a 

chmod 777 /usr/lib
touch /usr/lib/touchtest

into the Gnumakefile before the "install" call, pbuilder fails on the
"touch" command. This happens locally on my computer as well as in
Ubuntus build system.

What could be the cause?

Best regards

Ole