You are missing a couple of ENDIF. Each IF requires a corresponding ENDIF. Please see the KiXtart Manual for correct IF-ENDIF syntax.

Example
code:
$Drive='S'
$Share='\\stymie\Program Files'

If InGroup('accounting')
  ? 'Mapping drive '+$Drive+' to '+$Share
  USE $Drive+':' /Delete
  USE $Drive+':' $Share
  IF @ERROR
    ? ' Error mapping drive '+$Drive+' to '+$Share
  ELSE
    ? ' Map Successful'
  ENDIF
ENDIF
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There are two types of vessels, submarines and targets.