# basic question about irrelevance in statements about absorptive and spectral absorptive power

I have read that spectral absorptive power(a) is dimension less term and total absorptive power(a) is just a ratio hence it is also dimension less. But I also seen expression in many books that relation between 'a' and 'a' as [ a= (integration from 0 to infinity)a`.d(lambda)] but dimensions of both sides didn't match. Please help to find Where is problem?