Trying to rip from DVD Image

I'm trying to rip a DVD from a DVD Image. I gave the path of the DVD Image
in the Storage tab, and moved to the Rip Title tab. However, when I clicked
the "Read DVD Table of Contents" button, I'm shown an error that it couldn't
read the data, and asked me to make sure that I've inserted the DVD into the
disc. Presumably it's trying to access the disc directly even though I've
give the path to the Image. Is it an error, or am I doing something wrong?

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Thanks
Jeenu