Subscribe2 widget doesn’t appear in Widgets section?

Hi All: I downloaded and installed the widget that puts subscribe2 into your sidebar. I uploaded the file to the directory, and went to the plugins section and activated it. I then went to the sidebar widgets section, but there was no “Subscribe2” widget to drag. I’ve tried deleting the file and re-activating it, but for some reason the widget never shows up in the list. I’m using probably 5 other widgets and they’ve all worked flawlessly, but this one it doesn’t work on. Any ideas?

….yes, I’ve cut and pasted someone else’s post from another (resolved) thread, because I’m having_exactly_the same issue. So far it hasn’t magically fixed itself, though, as the other person’s problem did.

Anyone have thoughts on what might be happening?

Here’s where I got the widget:

https://subscribe2.wordpress.com/tag/installation/

I nosed around a little but can’t tell what version of the widget I’m using.

The subscribe2 plugin is active, and the sidebar widget is active.

Thanks