How does the precipitate look?
What you are doing _is_ wrong, for several reasons.
1. Have you really weighed 24.968 g of copper sulfate? It is a waste of time, as its composition (number of hydration waters) is never exactly known, so you can't be sure it is exactly 0.1 moles of the salt. Plus, even in the case of analytical grade reagents you can expect some impurities, which makes weighing with this accuracy unreasonable.
2. Do you really need 1.0000 M solution, or just 1 M solution - the latter means "something around 1 M" (what "around" exactly means depends on the application, but typically ±5% will probably do), the former is a standardized analytical solution.
3. Adding 24.968 g to 100 mL of water doesn't produce 100 mL of the solution, so its final concentration is not what you think it is. Actually it is quite likely you are exceeding the salt solubility.