what is the meaning of sampling fluctuation ??
how does it affect calculation of range ??

Sampling fluctuations are variations in different set of samples drawn from a particular universe/population. Range is affected by samples because it represents the difference between highest and lowest values in a series. Now, if the sampling fluctuations are higher in a series, then no particular range would be able to represent the series as it will keep varying with fluctuations in different samples of the same series.