If you're wanting the sum of all the matching conditions you should enter that formula in the same cell (Say A1) in each of sheets 1,2 & 3. The formula doesn't need to contain the sheet name since it will default to the sheet on which the formula exists. So just
Note that the second element you used "C1:C100" is not the usual way of defining the value to be checked. Excel simply assumes you mean the first cell in the C1:C100 range, hence that's all you need specify. So enter this as Sheet4!C1 and in that cell enter the value you're wanting to count.
In your summary sheet4 in the summation cell enter
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