You probably just didn't quite do it right. Let me give more detailed instructions and if I don't explain it well Joe can chime in because he is better at explaining grip related things.
There shouldn't be a difference in the end result of the two ways of setting your grip. The only real difference is how the skin is pinched/not pinched under your fingers. You probably just didn't seat the palm correctly.
1. Place your hand on the barbell so that the skin/callus area just at the base of your fingers is making contact with the barbell.
2. While maintaining this contact with the bar push your hand forward so that the skin is slightly dragged backwards, towards the base of your palm and your hand begins to bend around the bar.
3. While pushing forward bring the palm of hand onto the bar by placing the webbing between the thumb and forefinger around the bar and "palming" the bar.
4. You do this all at the same time.
5. You will then need to rotate the bar slightly away from you until the wrist is straight.
At least this is how I do it. The result should be really the same grip. It will feel different but it really is just that pressure is applied to the skin differently. Probably you skipped the "second step". I had to check for myself and try a few different things and this is the only thing I could come up with. If you don't do "step two" you cannot get as good a grip with the whole hand making firm contact. I didn't mention it before because I never really thought about it as steps and it really is all simultaneous. Hopefully I explained this in a way that makes sense. If not then hopefully Joe can help.