Hi, thank you for the suggestion. The problem was simpler, and I am posting this in case it helps others. I just didn't have sufficient permissions on the PicoScope device (whcih is represented as a some device file in /dev/usb/...etc). I solved it by adding my user to the group 'usb' (using Gentoo ...

OS: Gentoo Linux with kernel 4.4.6. Scope: PicoScope 5444B. trace.xml file: https://bpaste.net/show/ea9b59f902d2 'lsusb | grep -i pico' shows: Bus 003 Device 003: ID 0ce9:1019 Pico Technology The layout of /opt/picoscope/ directory is: ├── bin │   └── picoscope ├── include │   ├── libps5000-1.5 │   ...