57 is right, call Shaw to get them to check the connections and line for you.
It sounds like you have a bad termination. That or you are running an excessive amount of cable, but really, how far could it be to your garage?
I would check your connectors and if they are ok (no stray shield strands shorting out the center conductor and the center conductor is not too long or too short) then go over the entire length of the line and look for any damage that may have happened(cuts, nicks, twists or kinks or maybe even staples?). I found a line that was almost cut right through one time but for some reason I had no noticeable loss of signal. I cut out the damage and had the next Shaw Tech that came to my house put new terminals on it. He was happy to do it as that way they know it is done right. If they find everything checks out and you do need an amplifier, they will install the proper one for you, for free, as spitoon said.
Also try looking for a CATV button on the remote or in the menu. Failing that check to make sure the coax is connected to cable on the TV and not ANT. Your TV thinks its an old rotary dial TV from the 70s and only gets 13 channels.
Thanks for following up and letting us know. I had forgotten about the CATV or CABLE setting to check as I do it so automatically whenever I am helping people with setting up their equipment. I guess that is why it is so good to have forums like this so that we can all have each others backs.
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