My Minature Schnauzer ignores me a lot in the park

Hello.
I take my mini to the park nearly every evening. She loves to go all around the perimeters of the fence around the park. When I call her to come, a lot of the time she ignores me and sniffs around and will not come to me.

I was wondering what I could do to remedy the situation?

Thanks.

Penny Czapiewski

Other then this she is 5 yrs and a very well behaved dog.