My test for icing used for roses...
Take a little bit of the icing and roll it up in a ball and hold it between your first finger and thumb. Now squish the ball a little.
If it does not feel sticky or tacky to you, you need to make it more creamier. You can do this by adding more crisco, like mentioned above, usually about a tablespoon per cup of icing, or you can add piping gel, about a teaspoon per cup.
You need icing that is sticky or tacky, but where a lot of it does not stick to your finger, that could be too soft.
Another issue, is that often we don't squeeze the bag hard enough and/or are turning our flower nails too fast. This will cause the icing to pull and stretch creating the ruffled edge. So squeeze harder, work faster and think less about each individual step of the rose.