This is the Conference Management Project. It says to remove the counter variable declaration, the counter variable initiattion in the class constructor and the increment() method.
Not clear on this. Is that removing everything about the Counter and Increment?

It's the example in the Trail:
<apex:page standardController="Contact" recordSetVar="contacts">
02    <apex:pageBlock title="Contacts List">
03         
04        <!-- Contacts List -->
05        <apex:pageBlockTable value="{! contacts }" var="ct">
06            <apex:column value="{! ct.FirstName }"/>
07            <apex:column value="{! ct.LastName }"/>
08            <apex:column value="{! ct.Email }"/>
09            <apex:column value="{! ct.Account.Name }"/>
10        </apex:pageBlockTable>
11         
12    </apex:pageBlock>
13</apex:page>

First I entered it all by hand and it goes to a page with the title but no columns nor data. So I just copied their example and pasted it, still no data on the page, nor headlines, columns, etc. 
What is missing?
Thanks

I'm just getting the installation done. Appears to have installed. When I click on "Set Customer IDs" I get an error message"
System.DmlException: Update failed. First exception on row 0 with id 0011a000002pnXsAAI; first error: FIELD_CUSTOM_VALIDATION_EXCEPTION, Account Number is not numeric: [AccountNumber]

I must have skipped something, but don't know what. 

I'm stuck on Creating a Controller Extension.  My increment button is not displaying and I've started the exercise over from scratch now 3 times.
What am I missing that the button does not appear?

It's the example in the Trail:
<apex:page standardController="Contact" recordSetVar="contacts">
02    <apex:pageBlock title="Contacts List">
03         
04        <!-- Contacts List -->
05        <apex:pageBlockTable value="{! contacts }" var="ct">
06            <apex:column value="{! ct.FirstName }"/>
07            <apex:column value="{! ct.LastName }"/>
08            <apex:column value="{! ct.Email }"/>
09            <apex:column value="{! ct.Account.Name }"/>
10        </apex:pageBlockTable>
11         
12    </apex:pageBlock>
13</apex:page>

First I entered it all by hand and it goes to a page with the title but no columns nor data. So I just copied their example and pasted it, still no data on the page, nor headlines, columns, etc. 
What is missing?
Thanks

I'm just getting the installation done. Appears to have installed. When I click on "Set Customer IDs" I get an error message"
System.DmlException: Update failed. First exception on row 0 with id 0011a000002pnXsAAI; first error: FIELD_CUSTOM_VALIDATION_EXCEPTION, Account Number is not numeric: [AccountNumber]

I must have skipped something, but don't know what. 

Battle Station Trailhead -Step 4:Ad business logic
"Step Not yet complete... here's what's wrong: 
The validation rule does not appear to have the correct error formula. Make sure Exhaust Port Inspectors have > 150% utilization' 
Note: you may run into errors if you've skipped previous steps"

I am having a hard time on this one. The error I keep getting is  'Challenge not yet complete... here's what's wrong: 
The 'Phone__x' external object is not correctly setup with an indirect relationship to the User standard object.'

I followed the steps carefully and the Phone__x external object is setup with an indirect relationship to the User standard object. 

Any help would be very appreciated.