Cannot add VPC to my lambda function

Hi,

I've run into a problem where I can't add a VPC to my Lambda function. I followed the steps outlined in this Stack Overflow post (https://stackoverflow.com/questions/41177965/the-provided-execution-role-does-not-have-permissions-to-call-describenetworkint), but I'm still getting the error message "The provided execution role does not have permissions to call CreateNetworkInterface on EC2". Do you have any suggestions on how to resolve this issue?

PS: I've attached three permission to my IAM user: AmazonEC2ContainerRegistryFullAccess, AWSLambda_FullAccess, AWSLambdaVPCAccessExecutionRole.

Thanks!