Solver keeps ignoring nonnegativity conditions

Hi everyone,
I'm fairly new here and don't have much experience woth advanced Excel usage, but for a school project I am creating a document to deal with linear programming.

I am working with the solver extension and it keeps ignoring the nonnegativity constraint - I have both specified it as a constraint and marked it as a model specification in the settings/preferences submenu (both at the same time and also separately). So far it just ignores all of this and throws a bunch of negative outputs out.

any ideas on how to deal with this will be greatly appreciated

If you upload a sample file you stand a better chance of getting help.

Alf