When using multi-child select statement like the below:

SELECT ORG, C1, C2, ... FROM (
   (SELECT X FROM Y WHERE Z1 = xxx AND Z2 = :param1 AND DATE BETWEEN :param2 AND :param3) C1,
   (SELECT X FROM Y WHERE Z1 = yyy AND Z2 = :param1 AND DATE BETWEEN :param2 AND :param3) C2,
   ...
)
Then binding with report parameter will be like:
param1 = rpt_param1
param2 = rpt_param2
param3 = rpt_param3

The an error occurred while excuting the query in the datasource wizard.
Also, some time the wizard accepts the query but the preview mode will display the same error.
The error is "ORA-01008 : Not all variables bound"

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Workaround: Don't use the same query parameter in more than one child select statement. Create new datasource parameters per each select statement; then bind them all to the same report parameter. 

SELECT ORG, C1, C2, ... FROM (
   (SELECT X FROM Y WHERE Z1 = xxx AND Z2 = :param11 AND DATE BETWEEN :param12 AND :param13) C1,
   (SELECT X FROM Y WHERE Z1 = yyy AND Z2 = :param21 AND DATE BETWEEN :param22 AND :param23) C2,
   ...
)
Then binding with report parameter will be like:
param11 = rpt_param1
param21 = rpt_param1
param12 = rpt_param2
param22 = rpt_param2
param13 = rpt_param3
param23 = rpt_param3
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Products:
* Report Designer v2014.Q2
* Oracle Database 10g1, 10g2 or 12c
* Oracle Client: ODTwithODAC 12.1.0.1.0 Or Less