Why my wallet is out of sync all the time？

I downloaded gridcoin.zip,and launch Gridcoin-qt.exe,then colsed it.I put the gridcoin.conf in the data directory (C:\users\%username%\AppData\Roaming\Gridcoin),and I reboot Gridcoin-qt.exe.But the wallet still haven't any change after two hours.

The bottom right prompt:
"No block source available...
0 active connection to Gridcoin network"

My gridcoin.conf:

rpcuser=*******
rpcpassword=********
rpcallowip=127.0.0.1
rpcport=9332
server=1
gen=0
addnode=98.114.181.178
addnode=76.187.184.27:9778
addnode=66.187.94.194:9778
addnode=76.74.177.224:9778
addnode=84.125.196.167:9778
addnode=71.233.139.62:9778
addnode=72.92.48.105:97788


In addition, my other coin's wallet are all normal in sync.