Did you try both active and passive transfers in your FTP client?
--> yes i have tried both (its give me authentication error)
Is SELinux disabled?
--> yes it is disabled
Is this a physical server or a virtual machine?
It is a physical server...
to me it seems like the ISPconfig 3 and the pureftd are looking a different directory for username and password....
I am not sure how to check if the are looking at the same files... Thanks