Unable to select partial duration for "add logo filter"

[avidemux]

This YouTube video pretty well shows what I'm trying to do; use Avidemux to add an image on top of my video where desired. But although I can add the image I have no control over the duration - it extends through the whole thing. Clicking on the "partial" button for the logo filter has no effect; I can only configure the image, not set a length of time for it to appear as shown in the referenced tutorial. Any suggestions would be appreciated!

[AQUAR]

With 2.6 the partial filter only works when the video filter doesn't have some time dependancy.
I would think that just overlaying a logo should be able to be done with the partial filter.
If the codec is not AVC then try to use 2.5.6.