asterisk users - Sep 2008 - ast_func_write: Function not registered

hi all , please need help for an
asterisk version 1.4.21.2

i created a write func odbc list records files in sql table:
[R]
dsn=connector
write=INSERT INTO ast_records (filename,caller,callee,dtime) VALUES
('${ARG1}','${ARG2}','${ARG3}','${ARG4}')
prefix=M

and set it in dialplan :
exten => _0X.,n,Set(
M_R(${MIXMONITOR_FILENAME}\,${CUSER}\,${EXTEN}\,${DTIME})= )

i tried to add preload => func_odbc.so to load before extentions.conf
but when i excute it still have ast_func_write: M_R Function not registered:

 Executing [0343434 at admin:6] Set("IAX2/555-10991", "
M_R(/records/23-09-08-02-22_555_0343434.gsm,555,0343434,23-09-08-02-22)= ")
in new stack
[Sep 23 02:22:14] ERROR[3261]: pbx.c:1564 astr _func_write: Function  M_R
not registered

any suggestions ??
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