I have 3 datasets and i have to use them in 3 different crosstabs. First i started with 3 Detail bands with 3 subreports and in these subreports i put one crosstab in each summary band. But it doesnt work! i dont know how to continue. my jaspersoft studio knowledge is too small!
Add your subreports to the summary band. You will need a stub query in your parent report (select 1 from TRUE etc. - that depends on what type of db you're hitting), or a query that always returns records. An alternative to that stub query, you may be able to just set the report property - whenNoDataType="AllSectionsNoDetail" at the report level to always render your summary band.