JasperReport variable is displayed when preview supreport but in master report it's throw error evaluating expression for source text

I'm using TIBCO Jaspersoft® Studio 6.15.0 for building my report.

I have a master report and a subreport with jdbc connection,

The master report and subreport retrieve data from different pl/sql procedure.

When i create the subreport it's created in main folder not the master report folder,

then i have no errors, when i preview my subreport it's previewing ok like expected.

but when i preview the master report it's show the data but subreport section is blank,

the subreport don't show anything.

i moved the subreport to the same folder with the master report, and now I'm getting deferent

error. I have variables with BigDecimal data type in the subreort.

in master report i'm getting:

Error evaluating expression for source text: arFormatFactory.toArabicNum($V{NF}.format($V{TOTAL_1})) at net.sf.jasperreports.engine.fill.JREvaluator.handleEvaluationException(JREvaluator.java:294)

the $v{TOTAL_1} is a variable in supreport. and if i delete it the master report give me an error

on the next variable it's name is TOTAL_2.

the source is too long but here is the source in master report for sup report.

<subreport>
    <reportElement mode="Transparent" x="1" y="34" width="798" height="36" uuid="567d0996-6626-4985-ba8f-6bc3443b9561"/>
        <connectionExpression><![CDATA[$P{REPORT_CONNECTION}]]></connectionExpression>
        <subreportExpression><![CDATA["OMD_REP_ITEMS_BALANCES_SUB.jasper"]]></subreportExpression>
</subreport>

Any solution? ask me if you need more information.