OPK errors... any tips please?

Symyna
First time using digital Opks this month, I tried one yesterday and got an error...I followed the directions exactly, but I thought I might've done something wrong.  I tried another one this morning and late afternoon same error. The test stick icon blinked on right away and after about 7 min the below "book" icon showed up. The instructions say that's an indication of an error. I insert the stick arrow to arrow, hold the tip in urine for 15 seconds, put the cap back on, and lay it flat. I'm not sure what I'm doing wrong. Anyone else experience this and have any tips? Thanks for your input!