I have a problem with API. IP-Pool.

[AeroWave]

Good evening.
I have a problem with API.
I make inquiry for in advance created user:
<?xml version="1.0" encoding="UTF-8"?>
<packet version="1.4.0.0">
<client>
<ippool_add_ip>
<client_id>29</client_id>
<ip_address>192.168.0.1</ip_address>
</ippool_add_ip>
</client>
</packet>

I Receive the answer:
<?xml version="1.0" ?>
- <packet version="1.4.0.0">
- <client>
- <ippool_add_ip>
- <result>
<status>error</status>
<errcode>1013</errcode>
<errtext>client does not exist</errtext>
</result>
</ippool_add_ip>
</client>
</packet>

Checked many times

For the user under ID 1 IP the address is added normally. Help to solve a problem, please.