Hello Micael!
I don't know what was the problem. I was able to find the solution when I started writing the code bit by bit and checking whether that code would compile in fluent. I reached a stage where whole code could compile with the proper messages of file read and closed. Thank you.

Now I have one doubt, currently DEFINE_ON_DEMAND, for which I have to manually assign the values read in from the file to arrays. Is there a macro which does this automatically as soon as the loading of the library is over?