Is this Corrected Mass Flow equation correct?
The equations on Wikipedia are correct (see Flack, for example). I believe your error is in their interpretation. You say that you are given a mass flow rate and want to "convert [it] to a corrected mass flow rate at 10000 feet." But the direction you take the equations is as if you have a mass flow rate at 10000 feet and want to convert it to the mass flow at sea level. If the latter is what you intended, then I see no error. If the former, you need to invert the equation.