If you have installed powermail and you use another tool / extension which uses another javascript framework, you may want to deactivate the powermail use of jquery.
Write in constants:
plugin.powermail.js.validation = 0
If this isn't enough, like it was for me within powermail 1.6.3, than write in setup:
page.includeJSFooterlibs {
powermail_jQuery.external = 0
powermail_jQuery =
powermail_jQueryTools.external =
powermail_jQueryTools =
powermail_frontend =
}That should to the trick.
Bytheway try the fancy powermail css layout, it is nice and out of the box.