“analogWrite” was not declared in this scope

This error message typically occurs when you are trying to use the "analogWrite" function in Arduino, but it is not recognized by the program.

There are a few possible reasons why this might happen:

1. You may have misspelled the function name. Make sure that you have typed it correctly as "analogWrite" with proper capitalization.

2. You may not have included the necessary header file. In order to use the "analogWrite" function, you need to include the "Arduino.h" header file at the top of your program.

3. You may be using an older version of Arduino that does not support the "analogWrite" function. Check your version and make sure it is up to date.

4. You may be using the wrong pin number. The "analogWrite" function is used to output a PWM signal on certain pins that support it. Make sure that you are using one of these pins and that you have specified the correct pin number in your code.

Once you have identified the issue, you can take steps to correct it and get your program running properly.