This is the string I came up with which I want to use to rename my files. The string works perfectly fine in the copy command window. When I copy+paste it to the Rename Files window, it gives me the [EROR IN FORMATTING STRING SINTAX]. Does anybody know what the problem is? Do some formatting string functions just not work in the renamer?

Quite simply, you cannot have path separators in the middle of those $if() functions. Strings are separated into different path elements before processing. Empty path elements are automatically eliminated, so you don't have to worry about "blank" directory names anywhere in your path...

You might also want to have an alternative for %title%. Using $if2(%title%,%_filename%) might be a good idea, unless you are 100% sure you don't have any untagged files. It can't really hurt anyway.