In Calc failing to delete 'Increment' value

I have a spreadsheet imported to Libre from MS Office and cannot speed up spreadsheet entry as each cell increases by ‘1’ every time. I access sheet>Fill Cells>Series but the fig 109 on page 137 does not show. All I get is a box with directions i.e. left to right etc but the ‘series’ option is grey and not accessible.
I therefor cannot delete the increment value.
It has not happened before with this worksheet.
Can you help please?

fig 109 on page 137

Which reference are you talking about? Please provide a link to the document and some information about your operating system and LibreOffice version may be useful.

I am refering to the book Libre Office 5 Getting Started guide 5.2. Using 6.1.3.2 version
Operating Windows 10. Am using a one page spread sheet for 12 months as a monthly household account and wish to drag a cell across the sheet. Hope this clears my problem.

Hi

The increment zone is greyed when the current cell contains some text, a value entered as text (with a ' visible at the beginning of the cell in the formula bar, or in a cell formatted as text).

Are you sure that’s not the case?

Regards