Refusing to walk the rail

Question
Sorry about your sick horse.    She is getting absolutely awful!    Lunging her helps but she refuses to do anything.   I am not very experenced and have been riding for about 2 years.   I'm getting really fustrated.  She has been fine until about 2 months ago.   The instructor is really not incrediably helpful so that is really fustrating me.   My husband suggests having someone else ride her that she is doing this because she "has my number".   Maybe I need training in how to handle a difficult horse??   

Any input would be appreciated.
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The text above is a follow-up to ...

-----Question-----
I have a 16 yr old Morgan mare (almost 17) that has recently decided that she does not want to work the rail, especially walking.   Nothing seems to help and I had the advise to "beat it out of her" which I refuse to do.    I was thinking that I should maybe start out with walking patterns in the middle to establish who's in charge and gradually work towards the rail.  What do you think?   I have had her for about 1.5 years and will not get rid of her cause I love her.  We have shown in the past and she has always been a handful.   My instructor had me gallop her until she was exausted and then she somewhat behaved and worked the rail, but I certainly can not go into the show ring with a totally exhausted horse!   Any ideas?

Thanks
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Hello, I am so terribly sorry i could not answer b4..i was very busy with my sick horse.
But yes, i think you are on the right track with going from middle to the outside. Make sure you make it very obvious what you want her to do. After you've done the circling, from the inside to the outside ...if she really isnt getting the point, you might need to use a crop on her. Let me know how you make out!
Thank you

Answer
Hello!
You should try spurs on her. Start with light spurs, and if it doesent work, move up to more severe spurs. You can try a crop with her to. Hold it with your inside hand, and everytime she refuses to walk on the rail, give her a little tap. Tap her harder and harder everytime with it if she does not want to obey. If her bad behaviour proceeds, I would definitely look into professional help with her.
Thank you for the question