5110 flutters when turning it off via pins

I have an Arduino Uno, Nokia 5110, and LDR hooked up. The text displays fine on the screen. I am trying to write my code, example below, so that when the light is dim the display turns off and when it is light it turns on. It turns on just fine, but when I go to turn it off, the backlight will just flutter, as if turning on and off really fast.

If I wire it directly to power it works fine, so I am thinking I have an oops somewhere in my code. Can someone give me a hand as to where I may be going wrong?

void loop() {
   // Reading the pin A0
   // Going to use this value to see if condition right
   // to turn on the screen.
   photocellRead = analogRead(photocellPin);
   Serial.print("Analog reading = ");

   // the raw analog reading
   Serial.print(photocellRead); 

   // Check to see if we need to trun on or off the LCD
   // Thresholds for the photodiode
   // turn off the display when I am not in the room
   // turn it on when I am in the room
   if (photocellRead < 70) {
     analogWrite(bckLghtPin, 20);
     myGLCD.enableSleep();
     Serial.println(" - Dark");
   } else (photocellRead > 200); 
   { myGLCD.disableSleep();
   analogWrite(bckLghtPin, 255);
     Serial.println(" - Light");
   }

Do you have a current limiting resistor?

   } else (photocellRead > 200);

THIS is your entire else body. Comparing photocellRead to 200, and doing nothing if it is greater, and doing nothing if it is less, is useless.

   { myGLCD.disableSleep();
   analogWrite(bckLghtPin, 255);
     Serial.println(" - Light");
   }

On EVERY pass through loop(), this code is executed, regardless of how bright it is.

J-M-L, I do have a 1k resistor inline with the backlight.

PaulS, thanks for the tip on my (embarrassing) flawed logic. But than I am new and thanks for the tips. I will rework it this evening and try again.