Calorie prolapse..

Scenerio: I usually try and lift weights 4-5 days a week, alternating between legs then core/arms. Now I do have a HRM (Polar FT40) but I've been told and have read that a HR monitor isn't accurate when it comes to "machine" weight lifting. Usually my sessions are only 20 minutes (with 40 minutes of cardio for a total of 60 minutes at the gym). Most sites, that I have ran across, that have the weight lifting/calorie calculator don't have the "machine" version option.

My calorie intake is set to 1490 which should promote a 1lb/week weight loss. I do eat back all my "cardio" burnt calories, or at lease most of them.

So my question is, is it okay that I don't add weight lifting to my daily calories burnt?