Get List of Azure Vms in a web page

Hi, I wanted to list out all azure VMS in a web page using Asp.Net, C#, I have implemented the concept with REST API, Authentication gets success but while taking VM list getting an exception like,  Additional information: The client with object id does not have the authorization to perform action 'Microsoft.Compute/virtual machines/read' over scope '/subscriptions/

I checked in Azure Port, our subscription id has the following roles  Owner and Virtual machine Contributor

why I am getting this error, please anyone advise me on this 

thanks in advance