F # compilation issues fixed after changing file position back and forth and strange naming behavior

I am using the Power F # tools which give me a convenient way to create folders in an F # solution.

Now I have 2 similar console app projects in a solution. Both projects contain a util folder. One project folder contains a named module with functions. Another project utility folder contains the enum name and class definition.

The namespace is done like this: ProjectName.Folder

Both projects have a Program.fs file with the main EntryPoint function. Program.fs is the last file in the solution. The main function is inside the ProjectName namespace.

Since both files have the same root namespace, I expect to see the subnamespace from Program.fs when I try to "open" the subnamespace and use code from another file.

Ok, that works in the first project with a module, but not another that contains class definitions in the sub-namespace ... when I try to open the sub-namespace in the second project, I need to provide a fully qualified namespace, even though both files have one and the same namespace root.

In the first project, I can directly reference the sub-namespace without specifying the root namespace - it's just visible.

This confuses me, especially since sometimes I have compilation problems which I solve by moving the Program.fs file with main () up and down in the project, and suddenly I can compile.

Do you have any ideas if the problems described are related to problems in the project structure (file) that are not visible in the solution explorer, or I don't see something related to the F # syntax and how to use (open) modules with a namespace with functions that work versus for class names (types)? Could it be that F # powertools is somehow causing problems when creating folders and files inside those folders?

I can provide code samples. They are mostly taken from the tutorial, but I wanted to keep the question as short as possible.

Edit 1

I just merged the code in a new project to test everything, and as it turns out, when I open with a namespaced module, it can only provide the namespaced relative path to that module, but when I open the namespace. in order to use the classes defined there, I need to provide the full path of that namespace, although I open this namespace from the same root namespace. Can anyone confirm this behavior? Meanwhile, I'm going to dig out http://en.wikibooks.org/wiki/F_Sharp_Programming/Modules_and_Namespaces