imported persons can't be found

[Prosper]

I imported a bunch of people via a csv-file, succesfully.
Later on, I wanted to assign them to a group, but they don't appear in the list, because it is only possible to search "all groups" or by group and they don't already have one...
I figured out, I have to create the group first, and then import this file directly into the group. But since they already exist, I get the notification "invalid username". How do I delete the first bunch if I can(t find them ?

[Prosper (prosper-nl)]

The problem might be more complicated: it seems something is wrong with the "import groups members" form. Neither a CSV-file or maually written data are excepted. The same file or same data (copy/paste from a textdocument) are accepted via the "import persons" form.
Behaviour is, as far as I can distinguish, not consistent, since I seem to have been able, once or twice to import members via the "import group members"-form. I think it was just after logging in, AND with the unnecessary step of first clicking on "edit members". A subsequent try didn't work out. Once it has rejected, it always does.
I have to say that imported persons now are visible in the list without yet having a group, which kind of invalidates my first bug-report. Still there is the problem with the import-form.

[Tom Hoffman (tom-hoffman)]

One bug is that we need a little explanation on the group members form about what format is expected and what you should expect this import to do.

Oh... are you getting the traceback when you import that says: Exception: DuplicateRelationship ?

[Prosper (prosper-nl)]

No,
it just lists each username saying it is invalid, like this
"exampleuser" is an invalid username.
Same CVS-file does import properly via "import persons".