Select all fields where fieldone is not equal to null + Propel

Select all fields where fieldone is not equal to null + Propel

I have a question about using the propel ORM and creating a query.
I have a table "locations" with fields:

location

sublocation

postcode

street

number

Now I want to select all the locations where the location field IS NOT
equal to 'null'.
How can I do this? I've tried this but I get back all the results ...
Tried query: $locations = LocationQuery::create()->where('location' !=
null)->find();