Variable accessibility in Matlab GUI

Hi,

I am importing data from Excel and storing them in Column Vectors in Matlab.

When I try to run a matlab File which uses this imported data for processing, it does not give me any trouble.

However, if i try to call this same Matlab File from a Callback method of a Push button, I get an error : 'Undefined function or variable 'variable name'.

I understand that, if you would have called a Function from the callback of a push button,it might not be able to aces it as functions have their own stack for variables.
Also, note that all the m files and the files related to the GUI are placed in a single folder.

Thanks!