Hi Fahad,
When using syms, you should break it down into symbols that are certain to be real valued and those that are not certain, and you should add the "real" qualifier when possible. For example,
syms Io Vo N real
syms Gamma %potentially complex valued
You should also add any assume calls that are reasonable. For example,
assume(Io >= 0)
With all of your symbols being potentially complex valued (because you did not say otherwise), and in case any of your values might be 0, MATLAB is unable to determine the complex sign of the expression. Hence, it gives the output in general about limits, with it not being able to prove anything about the properties of that limit.
So, make sure that you add all the reasonable assumptions so that MATLAB will be able to accurately determine the sign of the expression thereby giving an accurate result for the limit.