Softimage SDK Programmer's Guide > Script Development > Understanding Error Messages >

# ERROR : <tuple_name> is not defined

     # ERROR : Traceback (most recent call last):
    #   File "<Script Block >", line 12, in ?
    #     blinn, prevsrc = surface.ConnectFromFile( "$SI_HOME\Data\DSPresets\Shaders\Material\Blinn.Preset", prevsrc )
    # NameError: name 'prevsrc' is not defined
    #  - [line 12]

## Possible Cause

This is a message that can appear when you are trying to access a method's output arguments with tuple syntax but you have forgotten to initialize at least one of the variables you are using.

## Suggested Solution

You can just assign 0 or "" to each variable just to initialize it before using, regardless of what type it will eventually be (see Getting Output Arguments from Methods for more information).