There are many reasons why it took so long for Galileo's results to be confirmed, but these are the most important ones.
1. The church - at the time, the influence of the church was far greater than anyone else's, so if the church was against his findings, everyone else had to be as well.
2. The technology - it wasn't as developed as today, so there wasn't a way for those scientists to confirm whether Galileo was correct or not.
