Re: to realise vs to realising

Originally Posted by
chayanika
Dear Teacher,
Since I was ignorant about the forum rules, I posted the question below in an irrelevant thread. Hence I am posting it again in a fresh thread.
I was proofreading today when I came across a sentence that reads, " TPI is a leading model that provides an objective, step-by-step
guide to realizing business-driven test process improvement."
Can anyone please tell me, why it is
"guide to realizing" and not
"guide to realize"? 
I want to know which one is correct and why.
I answered that question in the other thread. Mark my mistake. Please don't start a new thread now.
Context is always important; labelling is rarely important.