change the comm on your computer.
Control Panel -> Device Manager ->find comm 7, right click select properties, Port Settings, Advanced, select a different comm number. For some reason it will usually saw 1 and 2 are used even though they are not. I believe Signblazer tops out at 4, so set the device to comm 1, 2, 3, or 4 and you should be able to get it to then work in SB.