Before you import files that are customized for the Captive Portal login, be sure to click the Customization link under Captive Portal on the left navigational pane and complete the steps listed there.
NOTE: The custom graphics file that you are importing (whether it be a GIF, BMP, JPEG) must be less than 20K in size to upload properly.
The steps to import your customized Captive Portal pages are as follows:
Should it be necessary to reset the system to the default settings, return to the Customization page and click Delete Files, and then Restore Default.