Can not display traffic chart

[kcchen5]

Hi Guys
Description :
The traffic chart display "-nan"


Error log :
/userap/home/cacti/bin/rrdtool: /userap/home/cacti/lib/libz.so.1: no version information available (required by /lib/libxml2.so.2)

But the /lib/libxml2.so.2 is exist , it is a symbol link , point to /lib/libxml2.so.2.9.1

[root@c2cacti01 ~]# ll /lib/libxml2.so.2.9.1
-rwxr-xr-x 1 root root 1448040 Mar 23 2015 /lib/libxml2.so.2.9.1

[root@c2cacti01 ~]# ll /lib/libxml2.so.2
lrwxrwxrwx 1 root root 16 Aug 16 10:38 /lib/libxml2.so.2 -> libxml2.so.2.9.1


I also create a symbol link to cacti/lib/libxml2.so.2 , but no working.
Any suggestion will be appreciated. Thanks a lot !!

Here is system information
Cacti version : cacti-0.8.7g
OS version : Red Hat Enterprise Linux Server release 7.2
PHP version : 5.4.16
libxml2 version : 2.9.1

If need any further information please let me know.
By the way , I have to install 0.8.7g to support my legacy plugin.

[Osiris]

Which plugin?

[kcchen5]

Which plugin?

Here is my plugin


I found the problem is not concerned with libxml2.so.2.9.1
It is relate to libz.so.1

First , backup libz.so.1.bak
mv /userap/home/cacti/lib/libz.so.1 /userap/home/cacti/lib/libz.so.1.bak
mv /userap/home/cacti/src/zlib/1.2.3/libz.so.1 /userap/home/cacti/src/zlib/1.2.3/libz.so.1.bak

Second , create symbol link
ln -s /usr/lib/libz.so.1.2.7 /userap/home/cacti/lib/libz.so.1
ln -s /usr/lib/libz.so.1.2.7 /userap/home/cacti/src/zlib/1.2.3/libz.so.1

After that , the error message no longer appear , but the flow chart is still blink , it shows "-nan"

I using the debug mode , the rrd tools says ok
Any suggestion will be appreciated

[Osiris]

Permissions? Cacti.log?