Putting a halter onto a 7year old Suri Female

We purchased a 7 year old Suri Female approx 12 months ago,she had been to shows and won various classes.
The issue is getting the halter onto her,I can put a halter above a bowl of chaff and she puts her head into it,but the moment I try and flick the strap around her head she goes ballistic.I can put the catch rope onto her no issues and I take her with the catch rope with no issue.She floats no problem and we can brush her,shear her with no issue.To me she has had a major scare and maybe when the previous people had her shawn.???I have elected to lead her with the catch rope although I probably need to make a more secure rope.
Any thoughts would be appreciated .