When you downloaded 4.15.1196 lsVM package, the file name is 104563118.lsVM-4.15.1156.zip. If you select this lsVM package under Firmware Management in STC GUI, you will not able to see and select any mXP interface. You will have to rename it to lsVM-4.15.1156.zip and install it. After you start to install, when you see the status "Downloading (40%)" in STC GUI, this status will be kept for a while (maybe 6-8 minutes roughly), then the status will be changed to "4.15.1156 is installed" directly, please note that it is done totally at this time (you will not see the percentage is increased to 41% or more). Then you can go to "Activate Test Module Profile", select "LS-Functional" to active it.
On the other hand, if you installed lsVM package unsucessfully, you have to re-install STC 4.15.1156 firmware firstly, then re-install lsVM package again.