Please see screenshot of error for query below and assist
SELECT
"Union"."Date" AS "Date",
"Union"."GL Number" AS "GL Number",
"Union"."Value" AS "Value",
SUM("Union"."Value") OVER(PARTITION BY "Union"."GL Number" ORDER BY "Union"."Date" ASC ROWS BETWEEN UNBOUNDED PRECEDING AND CURRENT ROW ) AS "Balance"
FROM(
SELECT
"tblJournal"."dteJournalDate" AS "Date",
"tblJournalEnt"."intGLNumber" AS "GL Number",
"tblJournalEnt"."decDebits"-"tblJournalEnt"."decCredits" AS "Value"
FROM "tblJournal"
LEFT JOIN "tblJournalEnt" ON "tblJournal"."lngJourID" = "tblJournal"."lngJourID"
UNION ALL SELECT
"tblJournalLY"."dteJournalDate" AS "Date",
"tblJournalEntLY"."intGLNumber" AS "GL Number",
"tblJournalEntLY"."decDebits"-"tblJournalEntLY"."decCredits" AS "Value"
FROM "tblJournalLY"
LEFT JOIN "tblJournalEntLY" ON "tblJournalLY"."lngJourID" = "tblJournalLY"."lngJourID"
UNION ALL SELECT
"tblJournalHist"."dteJournalDate" AS "Date",
"tblJournalEntHist"."intGLNumber" AS "GL Number",
"tblJournalEntHist"."decDebits"-"tblJournalEntHist"."decCredits" AS "Value"
FROM "tblJournalHist"
LEFT JOIN "tblJournalEntHist" ON "tblJournalHist"."lngJourID" = "tblJournalHist"."lngJourID")
AS "Union"