I realise there are several queries on here for this same problem but none of them provide a solution to my particular problem. 

I am running a web driver test that tries to fill out a form for a mail website to find postcodes based on address details. I keep getting this error when trying to locate the first text box:

```
org.openqa.selenium.NoSuchElementException: Unable to locate element: {"method":"css selector","selector":"#ctl00_BodyContent_txtBuildingNumber"}

```

I have used xpath and the id to try and locate the element but I keep getting the error. I can see that this element is present when the webdriver is running and I have been able to locate another text element on the page and enter text, but I keep getting this error for this field and other fields within the frame.

I am guessing that the problem must be to do with the fact that this field is part of an iFrame.

I have used implicit waits within the test but with no success. I still get the error.