Use of Pick list- when we schedule the service

I am scheduling service1 and the inputs to the service1 will be from picklist(the first one of picklist), and I am invoking service1 into the service2, and passing that variable (first from picklist) as an input to the service2.
but that variable value is null when I schedule the service. But when I execute or trace it manually it works fine. So my question is why this is happening when I schedule the service?
Can anybody help me please.


Services scheduled as tasks using Administrator cannot receive inputs. Administrator doesn’t provide a UI for specifying the inputs.

When the service is run in Developer, the inputs are gathered from you in the run dialog and passed to the service.

You can schedule a task using built-in services and set the input parameters. Refer to the reference guide for details.

Another approach is to code the service to use defaults if values are not present.