OK, I have some questions.
GLCD.print(Measured_Value);
You have not measured anything. Why are you printing something you haven't measured?
Measured_Value +=5;
So, it isn't a measured value. Why is the variable called Measured_Value?
then it much switch on digital output 2 as well. This means that digital output 2 and 3 is on at this stage. Now the reading is decreasing again. Once it reaches 20% both digital outputs switch off. Once the reading reaches 65% again, digital 2 switches on again. so it is still alternating between the two outputs.
Using names in the code makes it much easier to understand the problem/follow the description when reading the code.
Especially when you didn't post all of the code, so we can't see the relationship between variables in the code and numbers in the post.