Oracle Forms

db and dev 10grel2
hi all ,
i am trying to use text_io.fopen , and i am getting the error "ora-302000" , i've read that this error appears if i am not writing the complete path of the file i want to open , and that did not happen .
my file name is new and it resides into the f:\ drive , and i am writing this code :

declare

x Text_IO.File_Type;
BEGIN
x := TEXT_IO.FOPEN('f:\new.txt','R');
end ;

so why i am facing this error and the file does not open ?

thanks