screen keyboard does not appear reliable by touching text entry fields

Created text entry fields for User Name, Company etc. to use the entries as variables later.
Exported as HTML5.

Application will be used with tablets.

Problem: With the Chrome Browser (wich has to be used in this case) the screen keyboard does not appear reliable when touching the text-entry-field.

What I noticed:
- When it works with the first, it works with all other text entry fields on the same screen.

- Clicking in the address bar of the browser seems to get the screen keyboard on for nearly sure and it then stays (or comes up) also for the text entry fields in the captivate-Screens.

This is not exacly the same as the question here -> how to have tablet keyboard display when user taps text entry box , because in my case sometimes it works.