Gustavo -
I think the MAX() function is a part of your 0 result set problem.

i typically take sql statement [when reverse engineering it]
and write it out on big paper
and draw lines on functions, udfs, where() clauses, etc.

and i don't see any optimization available for your MAX() function.

I would suggest you include the MAX() function in your *WHERE* clause,
take it out of the field list, and see if you get the same results [0 result set) ..

if so - you have the wrong field for MAX() computation selected .
there are sql equivalents to MAX() - find one ..

regards [Bill]