RVN from RVN Wallet 3.0.0 can not be sent to another wallet

I have the RVN Wallet 3.0.0 app android mobile wallet, with mined RVN. 
I have the following problems: 
1- When I want to send from the RVN Wallet 3.0.0 app android mobile wallet to another wallet it shows me the following error message: Transport endpoint is not connected. 
Please I await your support to solve this issue. I am new in this and I do not know how to proceed.
Thanks and regards.