Ajax Validation not working properly in Android 4.0.x and lower-end android versions

We have an application where in after the user inputs a certain value in the input field, the validation happens in the back-end (Java). For this purpose, when a user enters a value in the input field, it registers an onchange event and as a result using ajax sends the value to java servlet to be validated. After validation if there is any error, that error is return and shown to the user. This works properly in Android 4.2, 4.3 , 4.1 i.e. higher end android versions. However, in lower end android versions(like Android 4.0), sometimes the response does not come. Some times when the user enters proper field value even then the error message is shown . But the same cannot be replicated in other android versions. It happens mostly in android 4.0.x and lower android versions.

This has been observed in Android 4.0.x(HTC,SonyErrikson etc) especially in the native android browser for that device

Can anyone let me know any reason for this ? Does ajax request work properly in such devices ?