I have new validation rule which is created , it works perfectly fine whenever we create a new record but it doesn't work when we edit previously created records . First the previously edited records are edited and saved and again when i try to edit them that's when the rule works. 

Where am i doing wrong 

We have a Reservation Object which has Check Box Fileds for the reservations( Monday , Tuesday , Wednesday etc) and we have a corresponding date field for which they made reservations ( monday date , tuesday date etc) . 

Department wants no user to make a reservation one week prior or make changes . If a user wants to make reservation for 1/9/23 , the latest they would be allowed is 1/1/23 to make reservation and on 1/8/23 they will be allowed to make any cancelations , that is unchecking the reservation value.

As a first step i wrote a validation rule 
OR (AND( Monday_Date__c  =  TODAY ()  +7 , ISCHANGED( Monday__c)),
AND(  Tuesday_Date__c  =  TODAY ()  +7 , ISCHANGED(  Tuesday__c ))

the above rule is not letting anyone to make changes for 1/9 reservation today but i need to check whether the rule will still work tomorrow 

the rule doesn't work when a new record is created. 

Please sugges where am i doing wrong
 

I have new validation rule which is created , it works perfectly fine whenever we create a new record but it doesn't work when we edit previously created records . First the previously edited records are edited and saved and again when i try to edit them that's when the rule works. 

Where am i doing wrong 

We have a Reservation Object which has Check Box Fileds for the reservations( Monday , Tuesday , Wednesday etc) and we have a corresponding date field for which they made reservations ( monday date , tuesday date etc) . 

Department wants no user to make a reservation one week prior or make changes . If a user wants to make reservation for 1/9/23 , the latest they would be allowed is 1/1/23 to make reservation and on 1/8/23 they will be allowed to make any cancelations , that is unchecking the reservation value.

As a first step i wrote a validation rule 
OR (AND( Monday_Date__c  =  TODAY ()  +7 , ISCHANGED( Monday__c)),
AND(  Tuesday_Date__c  =  TODAY ()  +7 , ISCHANGED(  Tuesday__c ))

the above rule is not letting anyone to make changes for 1/9 reservation today but i need to check whether the rule will still work tomorrow 

the rule doesn't work when a new record is created. 

Please sugges where am i doing wrong
 

Create a Visualforce page without the standard Salesforce header and display an image using the Visualforce image component.
The page must be named 'DisplayImage'.
It must NOT display the standard Salesforce header.
It must use a Visualforce apex:image component to display this image - https://developer.salesforce.com/files/salesforce-developer-network-logo.png

<apex:page showHeader="false" title='DisplayImage'> 
    <apex:pageBlock >
        <apex:image url="https://developer.salesforce.com/files/salesforce-developer-network-logo.png"/>
    </apex:pageBlock> 
</apex:page>

Challenge Not yet complete... here's what's wrong: 
The 'DisplayImage' page was not found.