blender 2.61
Linux server 3.1.9-1.4-desktop #1 SMP PREEMPT Fri Jan 27 08:55:10 UTC 2012 (efb5ff4) x86_64 x86_64 x86_64 GNU/Linux

Trying to add a sequence plugin fails. When doing RMB->Add Effect Strip->Plugin on Strip A, blender reports

Sequencer plugin "/home/userdir/dir-containing-Strip-A/" could not load

in the info-Window and in the console it reports

var1: /home/userdir/dir-containing-Strip-A/, var2:/home/userdir/dir-containing-Strip-A/, var3: /home/userdir/dir-containing-Strip-A/: cannot read file data: Is a directory