ok guys, I never had problems with this.
but I was used swaret to update my slackware machine, until in sudden this happends

you need sed to run swaret.

so it can't find sed anymore, so I tried to reinstall sed.

than this error occured.

configure:1302: checking for a BSD-compatible install
configure:1356: result: /usr/bin/ginstall -c
configure:1367: checking whether build environment is sane
configure:1392: error: ls -t appears to fail. Make sure there is not a broken
alias in your environment
configure:1405: error: newly created file is older than distributed files!
Check your system clock

my system clock is perfectly with ntp

what is the problem, and what can I do to help it

The clock issue usually has something to do with conflicts between the distributors machine and yours, but it seems to me that your build environment is not sane. Try getting around the clock issue and see what happens. You can get around it by going to the top level source directory (that configure is in) and running 'autoconf'. If that doesn't work, or you don't have autoconf, here's a failsafe alternative:

for i in *; do
test -f $i &&
echo >> $i
done

verigoth