This error could occur if the link between the Reporter Engine job and scheduled report is lost in database.
The engine jobs are stored in SQL table ncjobcfg and scheduled report in table rpauto.
For Engine Reporter job, the column jocont of table ncjobcfg contains the Scheuled Report object id.
If this column contains 0, the error "Error calling Reporter interface [#7]" occurs.
With Microsoft SQL Server Management Studio, execute following SQL request to check all Scheduled Report Engine jobs :
SELECT n.jobid, n.joname, a.objid, a.objname, n.jocont
FROM ncjobcfg n, rpauto a
WHERE n.jotype=31 AND n.jobid=a.schobjid
In this example "Reporter Job - Asset or User Report " is correct as objid 615 is present in jocont column.
But "Reporter Job - Asset or User Report " is not correct because jocont contains the string 0 (instead 614) :
All Scheduled Report Engine jobs with jocont=0 are not correct.