'#' character instead of farsi characters in result of built pdf by jdocbook-plugin

[mofarn]

I'm trying to build a Persian (Farsi) book by jdocbook-plugin, but in generated pdf file, Farsi characters converted to the '#' character. I have some errors like these in console-fa-pdf.log file:

Glyph "?" (0x62a, afii57418) not available in font "Helvetica".

Glyph "?" (0x648, afii57448) not available in font "Helvetica".

Glyph "?" (0x686, afii57507) not available in font "Helvetica-Bold".

Glyph "?" (0x643, afii57443) not available in font "Helvetica-Bold".

So i think it's font problem. so what should i do? (how can i change pdf fonts?)

Note: publican generates my pdf without any problems.

My plugin configuration:

<build>
  <pluginManagement>
    <plugins>
      <plugin>
        <groupId>org.jboss.maven.plugins</groupId>
        <artifactId>maven-jdocbook-plugin</artifactId>
        <version>2.3.9</version>
        <extensions>true</extensions>
        <executions>
          <execution>
            <phase>pre-site</phase>
            <goals>
              <goal>generate</goal>
            </goals>
          </execution>
        </executions>
        <dependencies>
          <dependency>
            <groupId>org.jboss.pressgang</groupId>
            <artifactId>pressgang-xslt-ns</artifactId>
            <version>3.1.3</version>
          </dependency>
          <dependency>
            <groupId>org.jboss.pressgang</groupId>
            <artifactId>pressgang-jdocbook-style</artifactId>
            <type>jdocbook-style</type>
            <version>3.1.3</version>
          </dependency>
        </dependencies>
        <configuration>
          <sourceDirectory>${project.basedir}/doc/zrm</sourceDirectory>
          <sourceDocumentName>${docname}.xml</sourceDocumentName>
          <masterTranslation>fa</masterTranslation>
          <imageResource>
            <directory>${project.basedir}/doc/zrm/fa</directory>
            <includes>
              <include>images/**</include>
            </includes>
          </imageResource>
          <formats>
            <format>
              <formatName>pdf</formatName>
              <stylesheetResource>classpath:/xslt/org/jboss/pressgang/pdf.xsl</stylesheetResource>
              <finalName>${docname}.pdf</finalName>
            </format>
            <format>
              <formatName>html</formatName>
              <stylesheetResource>classpath:/xslt/org/jboss/pressgang/xhtml.xsl</stylesheetResource>
              <finalName>index.html</finalName>
            </format>
          </formats>
          <options>
            <xmlTransformerType>saxon</xmlTransformerType>
            <xincludeSupported>true</xincludeSupported>
            <docbookVersion>1.76.1</docbookVersion>
            <useRelativeImageUris>true</useRelativeImageUris>
          </options>
        </configuration>
      </plugin>
    </plugins>
  </pluginManagement>
  <plugins>
    <plugin>
      <groupId>org.jboss.maven.plugins</groupId>
      <artifactId>maven-jdocbook-plugin</artifactId>
    </plugin>
  </plugins>
</build>