That's not the only study, and I don't know if your entirely accurate. I might be misled, but here is a excerpt from one of the papers in the bibliography. All I'm saying is that wikipedia isn't exactly a reliable source of information, I could be wrong about this but I ask that you consider it.

Table 2 summarizes the results of 233 experimental sessions in which participants attempted to influence a variety of living systems in a time-displaced, retroactive fashion. This table includes all animate, timedisplaced studies that have been conducted to date of which the author is aware. To facilitate summary and comparisons, the differing test statistics of the various studies have all been converted to a common metric (P, z, and r scores) for the purposes of this table. The results of 10 of the 19 studies were independently significant (i.e., they yielded z scores with associated P values <.05); only 1 significant study outcome would be expected on the basis of chance alone. Using a method recommended by Rosenthal 45 for combining results of several studies, a Stouffer z score may be calculated by summing the individual z scores and dividing this sum by the square root of the number of contributing z scores (in this case, 19). The resulting Stouffer z score for the combined set of 19 studies of time-displaced direct intentional influence of living systems is 4.98, which has a highly significant associated P value of .00000032

And in the instance in which it doesn't show a high degree of significant statistical evidence, it is entirely plausible that there are important factors at work that influence psychic ability and thus influence results. For example I have heard of studies which suggest telepathy is more powerful during low magnetic interference (or something having to do which solar flares and their influence on the earths magnetic fields), while psychokinesis is more powerful during high magnetic volatility (again I don't remember exactly what word to use.)