Print the last pages of a multi-page document

I have a document that is dynamic in the total pages depending on what staff choose for answers to questions.

I want to print just the last 22 pages as those will always be the last 22 pages

I have the following code but when the program runs and the print dialogue box comes up it is always ticked to print all the pages

I even tried to change the nStart and nEnd to positive numbers - the same thing

what am I missing. The code to delete after printing works.

print({
bUI: true,
nStart:-22,
nEnd:-1,
bSilent: true,
bShrinkToFit: true,
});
this.deletePages(this.numPages-22, this.numPages-1);
}

}