Creating a user using the API

Hello, 

I'm trying to create a regular user with the User endpoint in the API and I'm trying to do this with the least params as I can. 

This is my request:

<Set operation="add"><User><Username>xxx</Username><Name>xxx</Name><Password>xxxx</Password><UserType>User</UserType><EmailList><EmailID>xxx@gmail.com</EmailID></EmailList><Group>Guest Group</Group><SurfingQuotaPolicy>Unlimited Internet Access</SurfingQuotaPolicy><AccessTimePolicy>Allowed all the time</AccessTimePolicy><L2TP>Disable</L2TP><PPTP>Disable</PPTP></User></Set>

I tried to start with only the mandatory items, but in the end, I added more, but it's no use.

my version is 17

Please help

thank you