Hello,
Since "error 76" means it can't open the file, I suggest you might either be in a directory that can limit access to software (Windows\System32 folder, for example, is typically a bad choice to store iso since it can trigger Windows access limitations), or has a long path that WIT might have issues to "read" (try putting your "bin" folder at the root of your disk).
Or it can simply be that your file name is different! Any space between "earth" and "seeker", maybe? Sometimes it's as simple as that!
To ensure wit is correctly installed on your disk, just type "wit" (without quotation marks) in your command menu : you should get the following screen :
View attachment 321220
Please try to move your folder and rename your iso, and let us know!
Yours truly.