Well you have to understand that the 'parent' names are not that simple. Each one is different for each addon, etc...
Ripped from the wiki...
Code:
How to find a frame's name
Put the following in a macro: /print GetMouseFocus():GetName()
Use the macro to get the name of whatever frame your mouse is hovering over
DON'T use this on an unlocked eePanel. You'll get a name like eePanelGuideFrame1 if you do. The actual panel name would actually be eePanel1 in this case.
Note: If you would like your eePanel to resize when it's parent does, you may do so by attaching a script to it. See the eePanels Scripts page for an example.
Note2: Some problems may arise when attempting to parent a panel to another addon's frame. This usually has something to do with frames not being created when the eePanel needs to reference them. See the eePanels Scripts page for other ideas on how to make panels appear when you wish them to.
If you are using 'Pitbull' you might need to consult the
eepanels2 Official Thread because I believe the parenting of those specific frames are a little different.