Hi @mdmarouf, sorry to hear about your issues. Can you kindly confirm that you are using the On-screen keyboard as included with the latest Windows 10 Update that support Eye Control? (ie the link below):
https://support.microsoft.com/en-gb/help/4043921/windows-10-get-started-eye-control
As reported on this page, the only supported language so far is US International and indeed the software itself is not produced by Tobii, but I will raise the bug with the team here who may be able to pass it along to the relevant group at Microsoft.
In the meantime, as a workaround you could try using the regular onscreen keyboard that comes as standard with Windows 10 and use the Eye Control Mouse Widget to work with that keyboard. Not ideal as the buttons are smaller but you should be able to resize it accordingly.
In any event, I will speak with the developers to see if there another solution that can help you out. Thanks for your patience.