IIS custom 404 error, tips for entering URL addresses

iis| Error | Tips I set the custom 404 error in IIS, could not enter the URL address, always prompt to enter the "Wrong URL address, please enter a site's absolute URL address."
I typed it: http://www.xxxx.com/404.htm, but every time it was a mistake.

Repeated testing many times, and query the online data, found: IIS set 404 error, enter the URL address, to enter a site of the absolute URL address, is not a network domain name address.

The specific settings are as follows:
Open IIS Manager--> Click the properties that you want to set the custom 404 dot--> Click Custom error option--> select 404 Page--> Select and open Edit Properties--> set to URL--> url fill in "/404.htm" (Does not contain "")--> press OK to save the exit and then put the 404.htm this page in advance to upload to the site root directory with FTP.