pralines

I have always wanted to make pralines for Christmas, but I can never get them to set.  this is my mom's no fail recipe.  makes 2 1/2 dozen

1 1/2 cups granulated sugar
1 1/2 cups firmly packed light brown sugar
1 cup evaporated milk
1/4 cup butter
2 cups pecan halves
1 teaspoon vanilla extract

1. bring sugars and milk to a boil in a 3 or 4 quart saucepan, stirring often.  cook over medium heat , stirring often for 11 minutes or until a candy thermometer registers 228 (thread stage).
2. stir in the butter and pecans, and cook, stirring constantly, until candy thermometer registers 232
3. remove from heat and stir in vanilla.  beat with a wooden spoon 1 to 2 minutes or just until mixture begins to thicken and lose its gloss.  quickly drop by heaping tablespoonfuls onto buttered wax paper.  let stand until firm.