What is the percentage Chances of getting a tourist visa?

[aniethea]

I want to invite my sister and her daughter to visit me here and to have tour around California.
My sister is Married with two kids.
I am US Citizen living here for 12 yrs.
I don't work so my husband will be sponsoring their trip here.
Her husband will not be able to go with her because he manage their business and also her son will be goin to school that time.
They make good enough from their small business and their agricultural.
She already petition by my dad last 2011

Is their a chances of getting a US tourist visa?

She got denied 6 times. Her last try was 2011 and she wasn't petition yet, and still denied.

[roychoudhury@houston]

I want to invite my sister and her daughter to visit me here and to have tour around California.
My sister is Married with two kids.
I am US Citizen living here for 12 yrs.
I don't work so my husband will be sponsoring their trip here.
Her husband will not be able to go with her because he manage their business and also her son will be goin to school that time.
They make good enough from their small business and their agricultural.
She already petition by my dad last 2011

Is their a chances of getting a US tourist visa?

She got denied 6 times. Her last try was 2011 and she wasn't petition yet, and still denied.

Denied 6 times!!! Why? Normally any denial reduces the chance of getting a Visa