Above two data sources pulls data from same table(GLT0). You already checked data thru 0fi_gl_1 which is not fulfilled your needs. so check 0fi_gl_6 and check the data extraction at RSA3.
that may give some idea about required fields/data.
Even there is a best pdf with explanation about balance sheet p& l report.
find it from Google and explore it.
use Google search key as "Handling Balance Sheets and P&L Statements in SAP BW".