[Zope] DateTime....

Hi, My Problem, as mentioned before, is the defining of date boundaries to select entries from a catalog. Everything worked very fine when i just defined 1 date boundary. If I define two date boundaries (range:min:max style) i dont get back a single record. Has somebody expierienced this problem before? I took the information how to create this function from the Zope Book page 181. Please help me, i really dont know how to go on ! thanx, Sebastian