Import Leads With Existing Parent Account Id

Hello Experts,

First I want to say I'm a newbie to CRM Dynamics (And to any CRM tool)

I want to Import a list of leads. And I already know the Parent Account GUID for their leads. Below is the Mapping I used to do the import. Can anyone tell me whether this is the correct way to do it ?

I have the following columns in my Import csv file. Parent Account ID is the GUID of the account I want to add to these leads. 

And often I get Import failures saying a Duplicate Lookup Reference was found for Parent  Account Id. I suspect this has do something wrong with my mapping (As I have the Account GUID that needs to be mapped and that can't be Duplicated)

Any suggestions or corrections greatly appreciated.

Thank you