When you download some Third-party application software but cannot install it, you can follow these steps:
1. If we want to see whether the unknown source of the mobile phone is not open, we will click "Application" in the mobile phone.
2. Then click the "Set" option in the following figure.
3. Again we find the "more" button in the setting.
4. In more panels we will see a "Safe" button and click on it to enter.
5. Then here you will see that "unknown source" is unchecked and we select it.
6. When the "unknown Source" prompt pops up, click "OK".
7. At this time the unknown source is checked, the following figure:
When you set the above method or cannot install the software we can from several ways to troubleshoot the reason, one is that you install the software is not compatible with this system (the mobile phone system for Android4.3), If the software compatibility system then I see if we downloaded the package is not lost or not apk format Oh, also if not, we can go to the official download a new version of the test, because some sites provide software download package has been modified OH.