Quark 6 | Strange behaviour of returned list?


I have got a Quarkscript which searches the text offset of a certain characterstyle of a very long text (appr. 130.000 words; 1.200.000 characters).
After a couple of pages the list returned gives a negative characterposition.
Is there solution for this or is there something limited?

List returned (check last number!):

{30923, 31284, 31661, 32035, 32406, -32761}

By this part of code:

tell page pageX
					--Pak referentie 1
					tell text box TextBox1
							set CharPos_1 to ((offset of (every text style range whose character style is NameStyle)))
							set firstCharPos_1 to (item 1 of CharPos_1)
							set secondCharPos_1 to (firstCharPos_1 + 2)
							tell story 1
								set firstCharRef_1 to (a reference to (character (firstCharPos_1 + 1)))
								set secondCharRef_1 to (a reference to (character (secondCharPos_1)))
								set ref1_1A to contents of firstCharRef_1
							end tell
						end try
					end tell
				end try
end tell