searching user notes?

how can you search for estimates using creation dates and user notes? i keep getting these errors:


SSS_INVALID_SRCH_FILTER An nlobjSearchFilter contains invalid search criteria: createddate.

SSS_INVALID_SRCH_FILTER An nlobjSearchFilter contains invalid search criteria: usernotes.


both of these are in the documentation, but neither works. here's the code i'm using:

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var today = new Date();
var yesterday = new Date();
yesterday.setDate(today.getDate() - 1);

var filters = new Array();
filters[0] = new nlobjSearchFilter('mainline', null, 'is', 'T', null);
filters[1] = new nlobjSearchFilter('lastmodifieddate', null, 'within', today, today);
filters[2] = new nlobjSearchFilter('custbody_last_user_note_date', null, 'onorbefore', today, null);
filters[3] = new nlobjSearchFilter('createddate', null, 'within', today, today);