It's necessary to check the cables that you have connected to the Slingbox at home to determine what the issue is and why you are getting no signal. Do you have a HDMI cable connected to the same cable box? If that's the case, have a look at this link,
Hope this helps
One evening I suddenly had no TV -- Slingbox was out , flashing lights for BOTH internet and power.
I checked all connections, reset the slingbox, even did a complete reset of modem and router --
but I had no signal passing to the tv.
I disconnected slingbox and everything worked normally so I knew it wasn't my cable feed.
My internet on computer use was perfect ...
Even though I tried another supply with the same ratings, nothing fixed the problem until I get the OFFICIAL Slingbox Solo power supply in the mail and tried that fix --- PHEEEW -- it was either that or the circuits were friend -- caught a break for once!