what version of spellcast are you using?
I recommend getting the latest version. (2.32 last I checked)
Also, make sure you update your resources files
There's an XML tools plugin that you can download for Notepad++ as well. This gives you an option in the menu under plugins, named "XML tools" ...which you can use to check for xml syntax errors (it also gives you other options for xml editing though). It tells you what lines have the errors, or if no mistakes or errors are found... it will say "No errors detected."
Although, I suppose Firefox could work too.
Also, note that 2.22 code will not work on spellcast 2.3X+ ...since the syntax/format is different.
However, this tool is helpful for upgrading your 2.22 code/format xml files to 2.30+ format.
http://windower.net/plugins/spellcastupdatexml.php