Dapper contrib: Why is the key not found?

I am trying to use the GetAll method of Dapper contrib. Even though I have set a Key in my entity, I get an exception:

GetAll only supports an entity with a [Key] or an [ExplicitKey] property

My entity:

using Dapper.Contrib.Extensions;
public class Customer
{
    [Key]
    int Recid { get; set; }
    public string Name { get; set; }

    public Customer()
    {

    }
}

And my Dapper method:

public IEnumerable<Customer> GetAllCustomers()
{
    using (connection)
    {
        connection.Open();
        return connection.GetAll<Customer>();
    }
}

What am I doing wrong?