Well probably the path is incorrect F:/Mybot... so try using this code it will store the register.ini file with the details that you want, it is also much safer rather the $nick $+ .ini file because there will be devices and /writeini issues because windows cannot write an file that exist on devices and if the $nick is an machine device there will be an unfixable error and will brake the code.

Code:
ON *:TEXT:!Name*:#MyRoom: { 
  writeini -n register.ini $chan $+ ~ $+ $nick Name $2-
  writeini -n register.ini $chan $+ ~ $+ $nick Register on
  notice $nick Your character name is registered. Step 2: $2- $+ , Get ready for more!
}