There is no guarantee that by using the Prayer Request Submitter, God will answer your prayers in the way you want Him to answer. If you're praying, for example, for a sick loved one to get well, he/she may not necessarily get well but he/she will have the inner strength to cope better with his/her illness. God always answers prayers in His own way and in His own time.
While there are many scientific studies on prayer that yielded positive results, there are also those which are inconclusive. This doesn't matter to those who believe in the efficacy of prayer. The bottom line is that PRAYER WORKS! How and why even science cannot fully explain.