wifes daughter refused

my wife is from thailand & we have been together 7 years & married 4, we both felt we are now financially ready & after me building our new house for our family (i have not been married nor have any kids) know we were ready to fetch her daugher 10yr old to the uk before she would move up a school from primary education.
we have just recieved the refusal for her visa which devastated my wife as we thought it wouldn't be difficult as we have a local school ready & happy to take her, we have never claimed any sort of benefits & have enough money to satisfy them, etc etc,
they say my wife has shown we have kept in contact via phone & visiting her every year but my wifes mother did not help in the interview saying she has looked after the child almost since she was born which most grandmothers even here in the uk do. they help out but they must have missinterprited what she said. also she never mentioned that the grandfather is under medication for a mental health problem nor that she was looking after an elderly great grandfather who is disabled. also she said my wifes sister & brother helped with my wifes daughter whilst she was in the uk, they have both left home now he to join the army & she is now married.
can anyone help with how we appeal to their decision
thanks in advance