Redsn0w 0.9.14b1 version has some error with downgrade. MuscleNerd announced they will fix these issue with Redsnow 0.9.14b2 and Redsn0w 0.9.14b2 will release next week. This new version may be release next Thursday. Look at MuscleNerd news with Twitter.
I think you will happy with fixing these issue with new release. As they told they released b1 version with baseband downgrade features. Some 3GS devices are refuced this baseband downgrade feature. Your comments is the best thing to develop b2 version. Dev Team will release next b2 version after update b1.
You can find download links form here this week.