subscribe by e-mail in conflict with slimbox and fancybox plugin

For some reason is the subscribe by email plugin in conflict with any lightbox plugin! i have always used slimbox plugin but now it stopped working. i've checked and the problem seems to be the subscibe by e-mail plugin. I have tried to "solve" the problem by installing fancybox but that plugin has the same issue. someone any idea how to solve this ??