x-axis label adjustment (negative value)

dear advisors,

i am having difficulty finding out how to adjust the x-axis label.

As you may see in the figure below, my x-axis labels are clustered and the numbers aren't horizontally oriented.

In order to rearrange the x-axis labels, i have used 'xticks' and 'xticklabels'.

However, the result after applying 'xticks' and 'xticklabels' cuts the minus values of x-axis off.

set(gca, 'XLim',[-20 40], 'XTick', -10:5:30 , 'XTickLabel', -10:5:30);

What may be the problem, and how may i correct it?

Thanks.