linux spb17.0 startup problem

hi, guys:

I want to launch the allegro inside the installed spb 17.0 as following: 

$:cd /opt/cadence/SPB17/tools.lnx86/bin/allegro_cshrc
$:csh
$:source allegro_cshrc
$:allegro &

the terminal shows problem like this :

/opt/cadence/SPB17/tools.lnx86/bin/apd.exe: symbol lookup error: /usr/lib/x86_64-linux-gnu/libXext.so.6: undefined symbol: _XGetRequest

and I have checked  that  this path: /usr/lib/x86_64-linux-gnu/    does have   libXext.so.6

so how should i do to make it right?

thanks in advance!