error C8014 : 'MSG' : identifier already defined [ in installshield 11.5 ]

[venu]

Hi everyone,
the most painful trouble i am getting when i try to compile the
following script ,
I am getting error 8014 - identifier already defined.

ERROR MESSAGE :
C:\Documents and Settings\venugopals\Desktop\Server_temp\Server\Script
Files\Setup.Rul(82) : error C8014: 'MSG' : identifier already defined
Setup.inx - 1 error(s), 0 warning(s)
ISDEV : error -4370: There were errors compiling InstallScript

MY RUL FILE :

function LogString( MSG )
STRING szTitle, szString;
number nvFileHandle, nvResult;
STRING szOutput, szTime;
begin
// Set the file mode to append.

OpenFileMode (FILE_MODE_APPEND);

// Create a new file and leave it open.
if (OpenFile(nvFileHandle, FOLDER_TEMP, LOG_FILE) < 0) then
if ( CreateFile(nvFileHandle, FOLDER_TEMP, LOG_FILE) < 0) then
// Report the error.
MessageBox ("Setup could not create an install log file
in " +
FOLDER_TEMP + ". Is there room on the disk or is it write-protected?",
SEVERE);
abort;
endif;
endif;

szFullLogPath = FOLDER_TEMP ^ LOG_FILE;

GetSystemInfo (TIME, nvResult, szTime);
//Sprintf(szOutput, "%s: %s", szTime, MSG);

// Append the message to the file.
if (WriteLine(nvFileHandle, szOutput) < 0) then
// Report the error.
MessageBox ("Log: WriteLine failed.", SEVERE);
endif;

// Close the file.
CloseFile (nvFileHandle);
end;

I have tried out
1.Unchecking the checkbox "Correct Text Case While Typing Language
Keywords"
2.Checked whether i have included the .h files multiple times
3.The function LogString has an end; for it

Please help me folks.

Thanks in Advance,
Venu & Nithin