use of sed

hi i am trying to update paremeter with date and timestamp..
my source file is like this Taxpr_Param.txt :

[s_m_TAXPR_AGG_F_DRILL_INC_5_5]
$$LOAD_DATE=03/09/2011  04:01:51
[s_m_TAXPR_AGG_F_MAIN_INC_5_5]
$$LOAD_DATE=03/09/2011  04:01:51

terget like this new_file:

[s_m_TAXPR_AGG_F_DRILL_INC_5_5]
$$LOAD_DATE=03/10/2011      06:31:37
[s_m_TAXPR_AGG_F_MAIN_INC_5_5]
$$LOAD_DATE=03/10/2011      06:31:37

my script is :

chmod 777 Taxpr_Param.txt
s_val=`date '+%m/%d/%Y%t%H:%M:%S'`
q=`cat Taxpr_Param.txt |grep "LOAD_DATE="|head -1`
time_val=`echo $q|awk -F"=" '{print $2}'`
sed "s@'$time_val'@'$s_val'@"g Taxpr_Param.txt > new_file

this is not working properly.
so please help me..

thank you in advance..

Remove the single quotes inside the sed command and try..Also sed flag g was misplaced..

sed "s@$time_val@$s_val@g" Taxpr_Param.txt > new_file

thank you michaelrozar.
i have tried that also but its not working..
can you please check and give the reply..

You would need to quote the variables to preserve spaces in between them..

chmod 777 Taxpr_Param.txt
s_val=`date '+%m/%d/%Y%t%H:%M:%S'`
q=`cat Taxpr_Param.txt |grep "LOAD_DATE="|head -1`
time_val=`echo "$q"|awk -F"=" '{print $2}'`
sed "s@$time_val@$s_val@"g Taxpr_Param.txt > new_file

If you just want to replace the date and do not want to store the values then try

sed "@LOAD_DATE@s@\(.*\)=.*@\1=`date '+%m/%d/%Y%t%H:%M:%S'`@" Taxpr_Param.txt > new_file