魔女縛りによって生意気なサブ

I'm having trouble tightening my corset, so call in Princess Dahlia to help out. She seems to be doing a very good job until I realise she's tying me *in* to the corset. While I'm struggling she takes advantage to tie me with rope. Fortunately, I'm a witch - and with a twitch of my nose, the magic is cast. I'm now free, and she is the one tied up. Why didn't I just use magic to tie my corset in the first place?