Is there any diff between platform dev1 and dev 401 ?
Could you please decribe.

I'm new to salesforce,I would like to know the difference between these two.Can anyone help me :) 

Below is my challenge from navigating buttons and links module.

Add a custom button to a contact.
To pass this challenge, create a custom button which opens a link to 'http://google.com/#q=<CONTACT NAME>' - where <CONTACT NAME> is the current contact's name. Then add this button to the default 'Contact Layout'.The custom button must be named 'Google Info'.
The custom button must dynamically insert the contact's name using the appropriate merge field.
The custom button must be added to the 'Contact Layout' page layout.

I hvae done everything , and if I click the button also showing google page with the account holder name.But still getting the below error message.

Challenge Not yet complete... here's what's wrong:
The 'Google Info' custom button was not found. Hint: Make sure that it is a Detail Page Button (not link) and that its added to the page layout.


Yesterday also for one challenge initially it gave error, later I refreshed and check challenge again it was fine.Not sure what is wrong in above case.
 

Below is my challenge from navigating buttons and links module.

Add a custom button to a contact.
To pass this challenge, create a custom button which opens a link to 'http://google.com/#q=<CONTACT NAME>' - where <CONTACT NAME> is the current contact's name. Then add this button to the default 'Contact Layout'.The custom button must be named 'Google Info'.
The custom button must dynamically insert the contact's name using the appropriate merge field.
The custom button must be added to the 'Contact Layout' page layout.

I hvae done everything , and if I click the button also showing google page with the account holder name.But still getting the below error message.

Challenge Not yet complete... here's what's wrong:
The 'Google Info' custom button was not found. Hint: Make sure that it is a Detail Page Button (not link) and that its added to the page layout.

How to add my trailhead badges to linked in profile.
After clicking add to my linked in, what to choose in profile edit page?

https://developer.salesforce.com/trailhead/force_com_introduction/data_management/data_import
In trail head challenge, after csv file imported and mapped accordingly as per the challenge condition, I'm getting the below error:

Challenge Not yet complete... here's what's wrong:
All the contact records from the CSV file were not found in the Org.

 

Below is my challenge from navigating buttons and links module.

Add a custom button to a contact.
To pass this challenge, create a custom button which opens a link to 'http://google.com/#q=<CONTACT NAME>' - where <CONTACT NAME> is the current contact's name. Then add this button to the default 'Contact Layout'.The custom button must be named 'Google Info'.
The custom button must dynamically insert the contact's name using the appropriate merge field.
The custom button must be added to the 'Contact Layout' page layout.

I hvae done everything , and if I click the button also showing google page with the account holder name.But still getting the below error message.

Challenge Not yet complete... here's what's wrong:
The 'Google Info' custom button was not found. Hint: Make sure that it is a Detail Page Button (not link) and that its added to the page layout.

Below is my challenge from navigating buttons and links module.

Add a custom button to a contact.
To pass this challenge, create a custom button which opens a link to 'http://google.com/#q=<CONTACT NAME>' - where <CONTACT NAME> is the current contact's name. Then add this button to the default 'Contact Layout'.The custom button must be named 'Google Info'.
The custom button must dynamically insert the contact's name using the appropriate merge field.
The custom button must be added to the 'Contact Layout' page layout.

I hvae done everything , and if I click the button also showing google page with the account holder name.But still getting the below error message.

Challenge Not yet complete... here's what's wrong:
The 'Google Info' custom button was not found. Hint: Make sure that it is a Detail Page Button (not link) and that its added to the page layout.


Yesterday also for one challenge initially it gave error, later I refreshed and check challenge again it was fine.Not sure what is wrong in above case.
 

Below is my challenge from navigating buttons and links module.

Add a custom button to a contact.
To pass this challenge, create a custom button which opens a link to 'http://google.com/#q=<CONTACT NAME>' - where <CONTACT NAME> is the current contact's name. Then add this button to the default 'Contact Layout'.The custom button must be named 'Google Info'.
The custom button must dynamically insert the contact's name using the appropriate merge field.
The custom button must be added to the 'Contact Layout' page layout.

I hvae done everything , and if I click the button also showing google page with the account holder name.But still getting the below error message.

Challenge Not yet complete... here's what's wrong:
The 'Google Info' custom button was not found. Hint: Make sure that it is a Detail Page Button (not link) and that its added to the page layout.

How to add my trailhead badges to linked in profile.
After clicking add to my linked in, what to choose in profile edit page?

https://developer.salesforce.com/trailhead/force_com_introduction/data_management/data_import
In trail head challenge, after csv file imported and mapped accordingly as per the challenge condition, I'm getting the below error:

Challenge Not yet complete... here's what's wrong:
All the contact records from the CSV file were not found in the Org.

 

How does one add the Salesforce Trailhead Badges (link) on their Linkedin Profile? When I edit my Linkedin profile where do I do this?
Thanks!