While developing in oracle i discovered that since it defines all the column names in upper case, when you try to access a variable in the filter with all lowercase names it fails obviously.
Would be cool if we provide a case insensitive variable search by default, eventually specifying double quotes in brackets for names to use in a case sensitive environment.
so [variable] can access Variable VARIABLE or variable field names
and ["VARIABLE"] can access only VARIABLE field name
(ps. don't count slashes, they are there to not interpret the name as trac internal link)