I have the following code. Why do I get an error when I call the Procedure MyProc ?

Sample code:
*-- MAIN
PUBLIC dDate_1

dDate_1 = DATE()

=MyFunc(dDate_1)
DO MyProc WITH dDate_1

RETURN
*-- End of main

*-- Function
FUNCTION MyFunc
LPARAMETERS dDate

*-- This works
? dDate_1,dDate
RETURN .T.
*-- End of Function


*-- Procedure
PROCEDURE MyProc
LPARAMETERS dDate

*-- This does'nt work. "Variable DDATE_1 is not found"
? dDate_1,dDate
RETURN
*-- End of Procedure