Error Messages/42425

Error Message

You have specified Self as the first parameter to Choice, i.e., the parameter named «I».  In 
this case since Self is Variable Selected_city, Choice expects Selected_city to have
a discrete domain with explicit values.  But the domain of Variable 
Selected_city is not discrete with explicit values.

Cause

The Domain Attribute for your choice variable is not properly defined. It needs to be set to either Explicit values, Copy from index, or an Expression that evaluates to be an unindexed list. When set to Explicit values, the possible options for the Choice pulldown will be listed in the domain attribute. When using Copy from index, the possible options are copied from another existing index in your model (in this case, you can also simply set the first parameter of Choice to be the name of your index, rather than using Choice(Self,...)).

Remedy

Open the Object Window for your choice variable and examine its Domain Attribute. Select Explicit values from the domain type pulldown and enter the possible values.