How can I solve camera calibration first example?

I'm doing camera calibration in matlab

but I have a trouble in doing First calibration example

in detail, I completed to Click on the Image names button in the Camera calibraiont tool window

but next step didn't display in matlab window

(next step : Basename camera calibration images (without number nor suffix) : )

so, I didn' enter the basename of calibration images and the image format

How can I solve this problem?

Please, replay answer the question