It is as simple as this . . .. .
In case if the person is really interested with you, definitely he will make his/her time to spend with you irrespective of their busy schedules.
No true person will find difficult to spend their time with their beloved ones ..
If you get the same kind of response even after you continuously following up with them just leave them for some time and watch patiently..If they come back to you since they felt that they were missing you, its well and good ,they still have you in their mind , if not just leave them.
Dont ever try to go behind sum1, even after you doing that , if the response is negative then its understood that they are trying to ignore you. .
NEVER DISTURB THE ONE's who are IGNORING you.
You'll loose your prominence in their life ..
Regards,
AJAY