I cannot add qmake to QtVersions in Tool->Build and Run

[DidaHarp]

I have Qt installed on my FreeBsd just now. Everything goes well, except I CANNOT build even one "Hello World" project! It says I have no valid kits. Then I open Tools->Option..->Build & Run->Qt Versions, and I choose "Add" trying to add one qmake manually. However, after I enter folder "/usr/local/bin/" and choose "qmake", it returns me an error dialog, which says "Qmake not executable: The qmake executable /usr/local/bin/qmake could not be added:". I am confused that I have the newest qmake installed as "/usr/local/bin/qmake" using "pkg install qmake". Everything is set correctly except qmake. The compiler is Clang, debugger is GDB, cmake is also OK, and, I have to tell you that, the above are all auto-detected and performed well. What's wrong with qmake?
So, what should i do now with qmake?
Anyone help?

[jsulm]

What happens if you try to execute qmake on the command line?
What does "file /usr/local/bin/qmake" say?

[DidaHarp]

@jsulm Well, when I try to qmake a project, the result is :
$qmake lumos.pro
QMAKESPEC has not been set, so configuration cannot be deduced.
Error processing project file: /usr/home/albus/Downloads/lumos/lumos.pro

[DidaHarp]

@jsulm Do I miss g++ installed?

[DidaHarp]

@jsulm It has no business with g++. g++ is installed, and even though not, I have clang++ still.