bigalex

The only way I know of to have a connection to multiple data sources is to use connection parameter(s).
Suggestion is:
Use one of the subreports as the main report or at least use the same data source (you can select the data source and then place on the main report query  something like- Select 1 from dual )
Create Parameter (i.e., $P{Subreport2_conn}) on the main report  to use for connection to the data source in Subreport2:Class: java.sql.Connection Is For Promting: Uncheck Default value Expression: java.sql.DriverManager.getConnection("jdbc:oracle:thin:@YourServerIP:YourServerPort/yourdatabase","UserID","Password") Not sure what your drive is; in my case, it is   jdbc:oracle:thin
Set the Connection Expression in Subreport2 to $P{Subreport2_conn} I was using the same approach to connect five different data sources from one report.
I hope this helps.

Have you tried to change the Class Type (i.e. dollar amounts - to java.lang.Double)  in JasperStudio Dataset and Query Dialog window?

JasperStudio adds _# to the file name if the same file name exists in derctory.
Tip: To stay organized, create a separate folder for each report in JasperSoft Studio (MyReports).

Variables ANO and ANO_ACT cannot be null  and must be evaluated. 
Expression:  $P{ANO}!=null? ($P{ANO}.equals($P{ANO_ACT}!=null ? (Integer.parseInt($P{ANO_ACT})-1+""): "ANO_ACT is Null")?$V{CAN}:new BigDecimal("0")): "ANO is empty"
See example below:
<?xml version="1.0" encoding="UTF-8"?>
<!-- Created with Jaspersoft Studio version 6.16.0.final using JasperReports Library version 6.16.0-48579d909b7943b64690c65c71e07e0b80981928  -->
<jasperReport xmlns="http://jasperreports.sourceforge.net/jasperreports" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://jasperreports.sourceforge.net/jasperreports http://jasperreports.sourceforge.net/xsd/jasperreport.xsd" name="String to Integer" pageWidth="595" pageHeight="842" columnWidth="555" leftMargin="20" rightMargin="20" topMargin="20" bottomMargin="20" uuid="c5f3f90c-4936-41e8-a034-b7a768ac9060">
    <parameter name="ANO" class="java.lang.String"/>
    <parameter name="ANO_ACT" class="java.lang.String"/>
    <queryString>
        <![CDATA[]]>
    </queryString>
    <variable name="CAN" class="java.lang.String">
        <initialValueExpression><![CDATA["CAN"]]></initialValueExpression>
    </variable>
    <background>
        <band splitType="Stretch"/>
    </background>
    <pageHeader>
        <band height="35" splitType="Stretch">
            <textField>
                <reportElement x="80" y="5" width="430" height="30" uuid="d99f10a3-6103-4987-ab25-33932aa27d2c"/>
                <textFieldExpression><![CDATA[$P{ANO}!=null? ($P{ANO}.equals($P{ANO_ACT}!=null ? (Integer.parseInt($P{ANO_ACT})-1+""): "ANO_ACT} is Null")?$V{CAN}:new BigDecimal("0")): "ANO is empty"
]]></textFieldExpression>
            </textField>
        </band>
    </pageHeader>
    <summary>
        <band height="42" splitType="Stretch"/>
    </summary>
</jasperReport>
 
 

Change your Title hight to 25. 

Page # by group:
Page # evaluation time : now
# Of pages evaluation time : group
Select Reset page number in the group footter.
2. Select group header and enter "new Boolean($V{PAGE_NUMBER}.intValue()==1)" into [Print When Expression]
3. Make IF statement in the text field for pages:  if  # of pages > 1 then "invoice + {number 123}+ continued" else page#

Add to the source code:
To remove header on export:<property name="net.sf.jasperreports.export.xlsx.exclude.origin.band.1" value="pageHeader"/>To remove footer on export:<property name="net.sf.jasperreports.export.xlsx.exclude.origin.band.2" value="pageFooter"/>