jira display field from a database with script runner not working

[Maikes]

Dear collegues from Atlassian Community, 

I'm new to Jira and Trying to get information from a database and display it with the support of script runner!! 

I tried  de following link tutorial: 

Select List Conversions, https://scriptrunner.adaptavist.com/latest/jira/behaviours-conversions.html#_walkthrough_pick_from_jira_issues; 

But is not working!!! 

Someone can help ? 

[I'm using a virtual machine with Tryal Licence]

my code behaviour

: [

import com.atlassian.jira.config.database.DatabaseConfigurationManager
import com.atlassian.jira.config.database.JdbcDatasource
import com.onresolve.scriptrunner.runner.rest.common.CustomEndpointDelegate
import groovy.json.JsonBuilder
import groovy.sql.GroovyRowResult
import groovy.sql.Sql
import groovy.transform.BaseScript
import javax.ws.rs.core.MultivaluedMap
import javax.ws.rs.core.Response
import java.sql.Driver
import com.atlassian.jira.component.ComponentAccessor
import com.atlassian.jira.issue.Issue
import groovy.xml.MarkupBuilder
import com.atlassian.jira.config.properties.APKeys
import com.atlassian.jira.component.ComponentAccessor
import com.atlassian.jira.config.properties.APKeys
import org.apache.log4j.Logger
import org.apache.log4j.Level
import com.atlassian.jira.component.ComponentAccessor
import org.apache.log4j.Logger 


getFieldByName("CostCenter").convertToSingleSelect(
        [
                ajaxOptions: [
                        url : "[machineIP]:8080/rest/scriptrunner/latest/custom/eventTypes",
                        KeyInputPeriod: 500,
                        formatResponse: "general"
                ]
        ]
)

]

The rest end point get's correctly the database data!! 

Best regards Mikes