Hi Mattheo,
it is hard to directly point out the reason. Are you using [b]subdomain rate budget[/b] or [b]Rate buget[/b]? Do you have DFE there?
Please note that the [b]subdomain budget[/b] is computed at the [b]perimeter [/b](lines in 2D models or areas in 3D models) of the element selection. However, [b]Rate Budget [/b]considers [b]all[/b](element selection :"surface"+ inside as well).
Best,
Jintao