Trouble with While Loops?

Has anybody had any trouble with While loops and using iTime, iStdDev etc type functions in these loops. I keep getting a problem where it will only calculate the value in the very first loop, the value then remains constant and does not update as time goes on.

Does anyone know why this occurs?

post your code so someone can look at it.

Hi my code looks something like this.....for example i want to calculate the Standard deviation everything 100 milliseconds.

double stdvalue;
While (IsConnected()){

stdvalue = iStdDev(Null, 0, 10, MODE_EMA, 0);
Sleep(100);

}

NOTE: This is just code i wrote in a second off the top of my head so im not sure if i have used the correct syntax. The values are all correct tho. ( I am at work)

In my calculations stdvalue equals the same thing and does not change. I know this has something to do with the shift part. For some reason these while loops do not allow these fucntions to shift accross??? I get the same problem with iTime. The first value is correct and then it stays that way and doesn't update as required.....i needed to use TimeCurrent(). Do you think i need to make a seperate function outside the loop and call it when nesessary????

Cheers

if this is for an indicator, the sleep function does not work. Sleep is only for EA's