Thanks for your answer, I'll post the relevant parts of the code. I am pasting the example only for one meeting creatin, the code is repeated many times for each meeting.
The thing is that I would like to use startdatetime and enddatetime as it is used in the default event creation page, but when I try to use it in my custom page I get the label without the fields.
Any comment?

We are having problems also saving events which are not all day events.... I guess it is something with the dates also but no idea...

THanks.

public class businessTripConfController {

    // Business Meeting Events
    Event businessMeeting;
    Event businessMeeting1;
    Event businessMeeting2;

  SelectOption Duration;
    SelectOption Duration1;
    SelectOption Duration2;

  // businessMeeting #1
    public Event getbusinessMeeting(){
    if(businessMeeting==null ) businessMeeting = new Event(type='Meeting', subject='Meeting');
        return businessMeeting;
    } 
    public void setbusinessMeeting(Event aevent){
        this.businessMeeting = aevent;
    }
  
    // businessMeeting #1
    public Event getbusinessMeeting1(){
    if(businessMeeting1==null ) businessMeeting1 = new Event(type='Meeting', subject='Meeting');
        return businessMeeting1;
    } 
    public void setbusinessMeeting1(Event aevent){
        this.businessMeeting1 = aevent;
    }
  
    // businessMeeting #2
    public Event getbusinessMeeting2(){
    if(businessMeeting2==null ) businessMeeting2 = new Event(type='Meeting', subject='Meeting');
        return businessMeeting2;
    } 
    public void setbusinessMeeting2(Event aevent){
        this.businessMeeting2 = aevent;
    }


<apex:page controller="businessTripConfController" tabStyle="Event">

    <apex:pageBlockSection title="Business Trip Owner">
                <apex:inputField id="busMeetOwner" value="{!businessMeeting.ownerid}"/>
            </apex:pageBlockSection>

              <!-- Business Meeting # 1 -->
            <apex:pageBlockSection id="busMeetSection" title="Business Meeting #1">
                <apex:inputField id="busMeetWho" value="{!businessMeeting.whoid}"/>
                <apex:inputField id="busMeetIsAllDay" value="{!businessMeeting.isalldayevent}" onchange="setRequiredDateTime(this,'{!$Component.busMeetActivityDateTime}','{!$Component.busMeetActivityDate}','{!$Component.busMeetDurations}')"/>
                <apex:inputField id="busMeetActivityDate" value="{!businessMeeting.activitydate}" />
                <apex:inputField id="busMeetActivityDesc" value="{!businessMeeting.description}"/>
            
THE PROBLEM IS HERE, INSTEAD OF USING THIS ITEMS AND MAKING ALL THE SCRIPT FOR THE DURATION I WOULD LIKE TO USE EndDateTime and StartDateTime

  <apex:inputField id="busMeetActivityDateTime" value="{!businessMeeting.activitydatetime}" />                
                <apex:selectList id="busMeetDurations"size="1" multiselect="false" value="{!duration}">
                    <apex:selectOptions value="{!durations}"/>
                </apex:selectList>
                <script>
                    var d = document.getElementById("{!$Component.busMeetActivityDateTime}");
                    var e = document.getElementById("{!$Component.busMeetDurations}");
                    var f = document.getElementById("{!$Component.busMeetIsAllDay}");
                    var g = document.getElementById("{!$Component.busMeetActivityDate}");
                   
                </script>               
            </apex:pageBlockSection>


code continuesss.... but it isnt important...