Friends,
Solution:
1) Each time we change the parameters inside the query, we have to refresh manually the Return $F value of the Expression that calls the plsql function in the property panel.
2) Make sure the parameters are in the same order than in the calling plsql function.
3) Here is the query syntax that returned the correct value:
select mysch.CF_CostPerTreatmentFormula (
$P{p_asset_id},
$P{p_plant_treated},
$P{p_treatment},
$P{p_treatment_method_abrev},
$P{p_date_from}, $P{p_date_to}
)
from dual
