Adding a new switch in client mode does not prevent it from propagating its incorrect VLAN information. A server synchronizes to a client if the client has the higher configuration revision number. You must reset the revision number back to 0 on the new switch. To be safe, follow these steps:
1). With the switch disconnected from the network, set it as VTP transparent and delete the vlan.dat file from its flash memory.
2). Set it to a fake VTP domain name and into client mode.
3). Reboot the switch.
4). Configure the correct VTP settings, such as domain, password, mode, and version.
5). Connect the switch to the network, and verify that it receives the correct information.