I have this String

```
s = "03:23 PM on 09/04/12"

```

I want to take out the ' on ' and replace it with just a space ' '. I thought the string's gsub method, along with regex, would be the best solution. I am just not sure why this wont work.

```
s ="03:23 PM on 09/04/12"
s.gsub(/ on /, ' ')
puts s
#=> "03:23 PM on 09/04/12"

```