Adjust interval between tick marks in a graph

It is impossible to adjust the interval between tick marks when displaying an horizontal axis with 2 categories (years and weeks). The following steps do not change the space between the tick marks.
• Select the graph;
• Chart Tools – Lay Out;
• Current selection – Horizontal (Category) Axis;
• Format selection;
• Axis options;
• Interval between tick marks: 4.
How can I change the interval for the tick marks to display a mark after every four weeks? Is this a bug or by design?

Thanks in advance.

Thanks, this solution worked for me.
The excellent attachment really helped.

I want more number of minor tick intervals on x axis, in case of percentage variation and not in date format.
So please help me for the same.

I want more number of minor tick intervals on X axis. How can i do this.