How true is the rumor that Pippa is blaming her older sister, Catherine, for the disappointing results of her book sales?

In a recent report, it was said that Pippa Middleton's party-planning book, Celebrate, is not doing so well in the Amazon best-selling book list. It is currently cold at the 177th spot even with the discount from £25 to £12.

The hard-headed younger Middleton seems to be overlooking her boring writing and typical suggestions in the book, as she is said to be blaming her older sister, The Duchess of Cambridge because of this outcome.

One reason why Pippa blames her sister could be due to the cancellation of her US book tour. Prince William allegedly put a halt into the promising North American tour because the royal couple is afraid it will jeopardize the privacy of Kate, who has just suffered from a media bashing (topless photos) not long ago.

Pippa's book is also not doing quite well in the US. The book is stuck in 303 in Amazon's list; an alarming position for Pippa and her publishers, Penguin Books. This result will also affect Pippa's decision to build a career as a professional writer.

"Her publishers have now gone quiet on plans for a second book - and a novel" said an insider in a report by EntertainmentWise.com.

The sales of her book are considered crucial as another opportunity was also scratched from Pippa.

"What's more, NBC has reportedly stopped chasing her for a royal correspondent role" added the source.

View the slideshow to see images of Pippa looking hopeful during her book's launch in London.

Also read:

Pippa Middleton Fail: Book Sales Slow, Critics Slam Writing [PHOTOS]