Jboss connection pool does not connect to the DataBase

I am using JBoss 7.1, and I am trying to create a Database Connection Pool through Application Server. Right now I am trying it with a mySQL Db, but I have also tried with a Postgre DB, but the error is still the same. The problem is that apparently everything is fine, the connections are done well, etc., but when I try to access my application by localhost, an error appears in my console that warns me that the connection to the database is wrong. He tells me that he can not find the tables I told him to access ...

My code is as follows:

Jboss standalone.xml.

                <datasource jndi-name="java:jboss/jdbc/exampleDS" pool-name="jdbc/exampleDS" enabled="true" use-java-context="true" use-ccm="true">
                    <connection-url>jdbc:mysql://127.0.0.1:3306/example?useSSL=false</connection-url>
                    <driver>mysql-connector-java-5.1.43-bin.jar</driver>
                    <pool>
                        <min-pool-size>10</min-pool-size>
                        <max-pool-size>100</max-pool-size>
                        <prefill>true</prefill>
                    </pool>
                    <security>
                        <user-name>root</user-name>
                        <password>password</password>
                    </security>
                    <validation>
                        <valid-connection-checker class-name="org.jboss.jca.adapters.jdbc.extensions.mysql.MySQLValidConnectionChecker"/>
                        <exception-sorter class-name="org.jboss.jca.adapters.jdbc.extensions.mysql.MySQLExceptionSorter"/>
                    </validation>
                </datasource>
<driver name="mysql-connector-java-5.1.43-bin.jar" module="com.mysql">
                        <xa-datasource-class>com.mysql.jdbc.jdbc2.optional.MysqlDataSource</xa-datasource-class>
                    </driver>

web.xml

<resource-ref>
        <description>example</description>
        <res-ref-name>jdbc/exampleDS</res-ref-name>
        <res-type>javax.sql.DataSource</res-type>
        <res-auth>Container</res-auth>
</resource-ref>

javacode

private ServiceLocator() {
    try {
        this.initCtx = new InitialContext();
        this.envCtx = (Context) initCtx.lookup("java:comp/env");
        DataSource ds = (DataSource)
                envCtx.lookup("jdbc/exampleDS");
    } catch (NamingException e) {
        ApplicationException apRE = new ApplicationException(ErrorCode.E_JDNI001, e);
        LogService.getLog().fatal(apRE.getMessage(), apRE);
        throw apRE;
    }
}

Finally, I start the Jboss server and access the application, and that is when the console mentioned problem appears. I've done these pool connections with Tomcat and Weblogic, and with both servers everything was perfect. I'm finding the problems with Jboss.

Could someone help me? Thank you very much in advance.