Did you try all the remotes for Triax available with Slingbox?
Did you try the files available at the file section? (from the above menu select File search and enter Triax)
For example giva a try the file for Triax ST-HD 527 prepared by Alan Richey.
https://www.hifi-remote.com/forums/dload ... le_id=9713
Make sure you upload the correct file.
JU, PK, PL, RV & JB. If you want to check your type you can verify your IR blaster version in the Slingbox Properties dialog. Then match the IR version number with the chip type using the chart below.
1=JU (old US boxes), 2=PL (current non-HD US boxes), 3=PK (never used), 4= RV (current non-US boxes), 5= JB (Slingbox Pro-HD) (Compatible with PL files)