Last Refresh Succeeded: null

I've encountered the problem for a while now.

At first, I thought it might be a temporary bug of the server but it keeps coming back.

BI Server refresh history says: Last Refresh Succeeded: Null

I've set a sequence of VBA execution every night, and the source files will be automatically placed in order the following morning. 

I guess since my PC has recently run out of RAM memory, so the gateway is at times automatically shut down while the auto refresh schedule is occuring. That's why when I click into the refresh history, it still says Refresh In Progress, but Succeeded:Null

I've tried refreshing and publishing from Desktop again. It's ok to refresh sources from BI Deskto, yet publishing it to BI Server get stuck at the Publishing Screen, I have to cancel all the times

Please offer me some help with this.