Dear friend Chloe Yew

To fix the error "Symbol declared but no values have been assigned" in GAMS software, you need to ensure that all the variables and parameters that you declare are assigned a value before they are used in the model.

Here are some steps you can take to fix the error:

1. Check all the variables and parameters declared in your GAMS model and make sure that they are assigned a value before they are used in the equations or constraints.

2. Assign initial values to all the variables and parameters that are not assigned a value.

3. Make sure that you have defined all the required sets, parameters, and variables before using them in the model.

4. Check for any syntax errors in your GAMS code, as this can also cause the "Symbol declared but no values have been assigned" error.

If you are still facing issues after following these steps, you can try consulting the GAMS documentation or seeking help from the GAMS community forums.