Problems with marking in Adobe Reader

Hello,

im currently experiencing a problem with the marker function in Adobe Reader. I'm only able to mark some letters or words.

For example:

Conveying or northward offending admitting perfectly my. Colonel gravity get thought fat smiling add but. Wonder twenty hunted and put income set desire expect. Am cottage calling my is mistake cousins talking up. Interested especially do impression he unpleasant travelling excellence. All few our knew time done draw ask.

I don't know wether it's the PDF or the Adobe Reader.

Would be very thankful for a solution.

Regards