I get a black screen too after the update;

$ /opt/qmltube/bin/qmltube
file:///opt/qmltube/qml/qmltube/main.qml:427:5: Type TitleArea unavailable
TitleArea {
^
file:///opt/qmltube/qml/qmltube/TitleArea.qml:56:5: Type SystemInfoArea unavailable
SystemInfoArea {
^
file:///opt/qmltube/qml/qmltube/SystemInfoArea.qml:18:5: Type BatteryIndicator unavailable
BatteryIndicator {
^
file:///opt/qmltube/qml/qmltube/BatteryIndicator.qml:2:1: plugin cannot be loaded for module "QtMobility.systeminfo": Cannot load library /opt/qtm12/imports/QtMobility/systeminfo/libdeclarative_systeminfo.so: (/opt/qtm12/imports/QtMobility/systeminfo/libdeclarative_systeminfo.so: undefined symbol: _ZN10QtMobility18QSystemStorageInfo13connectNotify EPKc)
import QtMobility.systeminfo 1.2

I am not too savy, any way to roll back?