Script task process element, initialising lookup column in new record

I am creating a new record:

var schema = UserConnection.EntitySchemaManager.GetInstanceByName("UsrTable");
var entity = schema.CreateEntity(UserConnection);
entity.SetDefColumnValues();
entity.SetColumnValue("UsrColumn", columnValue);
entity.Save();
var recordId = entity.GetColumnValue("Id");

and then creating a linked record in a related table:

var schema2 = UserConnection.EntitySchemaManager.GetInstanceByName("UsrRelatedTable");
var entity2 = schema2.CreateEntity(UserConnection);
entity2.SetDefColumnValues();
entity2.SetColumnValue("UsrTable", recordId);
entity2.Save();

I'm getting the following error referring to the `UsrTable` lookup column in `UsrRelatedTable` table when running the process:

Terrasoft.Common.ItemNotFoundException: Value "UsrTable" was not found.
   at Terrasoft.Core.Entities.EntityColumnValueCollection.GetByName(String name)
   at Terrasoft.Core.Entities.Entity.SetColumnValue(String valueName, Object value)
   at Terrasoft.Core.Process.UsrImportCustomersSubMethodsWrapper.DeserialiseJSONExecute(ProcessExecutingContext context)
   at Terrasoft.Core.Process.ProcessScriptTask.InternalExecute(ProcessExecutingContext context)
   at Terrasoft.Core.Process.ProcessFlowElement.ExecuteItem(ProcessExecutingContext context)
   at Terrasoft.Core.Process.ProcessFlowElement.Execute(ProcessExecutingContext context)

The question is essentially how to initialise a lookup column with a record Id.