Segment Editor Draw Tube effect disabled

Problem report for Slicer 5.6.2 win-amd64: HI Everyone! I am experiencing some problems with DrawTube function. The fiducials placement key is always disabled. (gray), therefore no fiducials can be placed to draw the tube. Both SegmentEditorEXtraEffects and MarkupsToModels extension are installed.
Slicer Version is 5.6.2.

Any suggestion?

Thanks a lot in advance!

francesca


Short addition, maybe helps: I have just noticed that also in the function Surface cut the fiducial placement key is disabled.