I am having an issue, for the last couple of days and I dont know how to fix it.

I have run all the test classes in production, when I open my developer console, the overall code coverage is 79% (of all production). I have created a test class that covers 2 classes that weren't covered before, raising the code coverage for 1 class to 100% and the second class to 92%
I am trying to deploy this test class, but I am getting an error saying that overall code coverage is 73%.

This doesn't have any sense, as this new test class are over 90%, if my overall is 79% this should actually increase my coverage not decrease it.

Is there anything that I am missing? or is there another way to find out overall code coverage, and my developer console is giving me the wrong overall?