how to apply clahe in 2014a version in matlab

iam trying to apply clahe to the extracted green channel of my image

i get the following errors

i have also attached the coding

cold anyone help me in this regard

Error using adapthisteq

Expected input number 1, I, to be two-dimensional.

Error in adapthisteq>parseInputs (line 416)

validateattributes(I, {'uint8', 'uint16', 'double', 'int16', 'single'}, ...

Error in adapthisteq (line 154)

[I, selectedRange, fullRange, numTiles, dimTile, clipLimit, numBins, ...