I'm not even a Lacerte user but just a guess, if you work through the QDLTCG Worksheet you'll end up looking up the non-QDLTCG income in the tax table instead of using the rate schedule (because it's under $100K).  If $1 jumps you from one row to the next the tax cost at that level is $11 (22% of the $50 spread).  It makes for some weird math that doesn't align with common sense (i.e. donate $1 to charity, save $11 on taxes).

Rick