a bug?? inside subscription by email plugin

I have tested the plugin and it doesnt work properly.
My problem is that when i put the plugin inside a widget, and enter tan email, the phrase "thanks you have joined our mailing list" appear, if i go to suscribers nothing appear, and neither i receive any email.

However if i use the "button Follow" it works properly. My mail is added to the subscribers list and i receive an email giving the wellcome.

may you help me.