Terraform throwing 401

Summary:

Using terraform to create a compute instance throws 401 even though i am Administrator

Content (required):

Error: 401-NotAuthenticated, The required information to complete authentication was not provided or was incorrect.

Suggestion: Please retry or contact support for help with service: Core Instance

Request Target: POST https://iaas.<>.oraclecloud.com/20160918/instances

Service: Core Instance

Operation Name: LaunchInstance

When I create a storage bucket with same provider /authentication its created without any issue but using the same for compute instance does not work.

OPC request ID: be3a5d29d0ef9ee6796aea38450f079c/65B406ADA1A2C9B0F18F468E60550497/4C90D57F2243F13B6B45BBA64974A77F