iron on sheets not ironing on

i have some laser iron on sheets, i have printed to the sheet but when i iron it to the pcb, only some of the traces are transfering to the pcb... (an faintly). what am i doing wrong?

I went thru that frustrating cycle. If you persevere, you will figure it out. The way I do it now is sandwich the PC board, transfer paper and a piece of felt cloth between sheets of glass. I use metal woodworking spring clamps with wood pads to not scratch the glass, to hold everything together. Set the oven temperature at 400 degrees F and put the sandwitch in for 10 minutes. When the sandwitch is cool, I soak the paper off in warm water.

thanx for the reply... wil try that next time i make a pcb