Converting lines to artistic media

Hi,

I've imported a logo to Corel Draw. The logo has several simple polylines. I'd like to convert them into artistic media in order to simulate calligraphic or hand made looking strokes. I pick the polyline, then I select Artistic Media from Effects menu. Then CD shows me the Default Strokes in a side docker window. I select any stroke. The polyline changes, but I can't modify the stroke width spinner. What am I doing wrong?. Is there another method to convert lines to artistic media without redraw them over.

Thanks in advance.