hello  everyone,
    my question is whenever i refresh the page in backend it perform DML operation(this code run beyond the concept(bug or error) so please check and comment here or there ) but when i click on save button at second time then it's showing a error message.

so link of my video is :
https://www.youtube.com/watch?v=-SlutmT3htw

<!--   VisualForcePage   -->

<apex:page Controller="AccountController" >
    <apex:form >
    <apex:pageBlock title="Account Details">
        <apex:pageBlockSection title="Details Section"    >
        <apex:inputField value="{!acc.name}" />
            <apex:inputField value="{!acc.phone}" />
            <apex:inputField value="{!acc.type}" />
            <apex:inputField value="{!acc.industry}" />
        </apex:pageBlockSection>
                <apex:pageBlockButtons >
        <apex:commandButton action="{!save}" value="save" />
        </apex:pageBlockButtons>
        </apex:pageBlock>
    </apex:form>
</apex:page>



// Controller

public class AccountController {
Account ac;
    public  AccountController(){
   ac = new Account();
    }
    public account getacc()
    {
        return ac;
    }
    public void save()
    {
insert ac;
    }
}

 

hi , i need some help in app customization specialist in challenge 4 (Report and dashboard). i make all report and dashbord but still it shows   Challenge Not yet complete... The 'My Top Volunteer Organizations' report should not be d

i dont understand 

Build Volunteer Tracker app reports

please help what i have to do

i dont understand 

Build Volunteer Tracker app reports

please help what i have to do

App Customization Specialist -  4 Build Volunteer Tracker app reports

I need some help; i don't understand what is expected ; which criteria for this filter ?

Challenge Not yet complete... here's what's wrong: 
The report 'Top Volunteers' is not using the correct filter.

Thks for your help !