Boris,

use this: SET LIBRARY TO (m_file). When you use macro substitution VFP just expands the string and trys to do this: SET LIBRARY TO C:\PROGRAM FILES\MYDIR\MYLIB.FLL. It will then stop after the first space and try to set the library to c:\program. You could use SET LIBRARY TO "&m_file" but this would be slower than using () to create a name expression.

>I try to install my application in "Program Files" folder, but in main programm I have the following code:
>
> programm_path = SYS(16,1)
> programm_path = LEFT(programm_path,AT(MYAPP,programm_path)-1)
>
> m_file = programm_path + "MyLib.FLL"
> SET LIBRARY TO &m_file
>
>but allways when I run application I receive the error messages: programm xxx.prg does not exist where the xxx is function from MyLib.Fll
>
>How can I use the long file names within the VFP.
>
>TIA
>Boris