problems with temporary variables in my Ado-file

Hi all,
I am pretty new to Stata mata language.
I am trying to write a program to estimate risk preference parameters.After defining the program and arguments, i have created
some temporary variables which i subsequently use to initialize the data as shown in the except below


program drop ML_eut3
program define ML_eut3
* specify the arguments of this program
args lnf r
* declare the temporary variables to be used
tempvar choice pa1 pa2 pb1 pb2 endow la1 la2 lb1 lb2 y0 y1 y2 y3 euL euR euDiff

quietly {
* initialize the data
generate int `choice' = $ML_y1
generate double `pa1' = $ML_y2
generate double `pa2' = $ML_y3
generate double `pb1' = $ML_y4
generate double `pb2' = $ML_y5

However when i call the program, stata returns an invalid syntax as shown below

rgs lnf r
- tempvar choice pa1 pa2 pb1 pb2 endow la1 la2 lb1 lb2 y0 y1 y2 y3 euL euR euDiff
- quietly {
- generate `choice' = $ML_y1
= generate __00000A =
invalid syntax
generate double `pa1' = $ML_y2
generate double `pa2' = $ML_y3

I am using the latest version of Stata and i look forward to your assistance