I find that "contribution" can be uncountable from dictionary?
why is it incorrect?
Because it is used here as countable. You rarely find it being used as an uncountable noun having an abstract meaning. In economics & business, specifically cost accounting, there is term called contribution margin or(simply contribution) used as a concept to analyze profitability of a business. It is the marginal profit per unit sale and applied to compute the break-even point which is expressed as the point where Total Contribution = Total Fixed Cost A business firm, whose total contribution falls short of total fixed cost, will go into red within no time.