Use of vlookup function results in "Improper assignment with rectangular empty matrix" Error

I am in the process of creating a GUI that will take inputs (values between 0 and 1) and using the vlookup function written by Zhiqiang Zhang (<http://www.mathworks.com/matlabcentral/fileexchange/29233-vlookup-similar-to-ms-excel-function/content/vlookup.m>) will output values from the third column of an invisible matrix in the GUI.

Here is a portion of the code that results in the error "Improper assignment with a rectangular matrix": XLookupTable has three columns: "Index", "C/Co", and "X". PRCRatios is a callback from a pushbutton. The goal is to lookup the PRCRatios values in Column 2 of XLookupTable and report the X values in the matrix "x_matrix".

% Call Lookup table & use C/Co values to get x from lookup table
L = get(handles.XLookupTable,'data');
k = length(PRCRatios);
for j = 1:k
 content3(j) = vlookup3(L,PRCRatios(j),2,3)
end
x_matrix = transpose(content3)

Here is the code for the XLookupTable:

index = 0:700000;
xlookupCol1 = index.*0.001;
xlookupCol2 = exp(xlookupCol1).*erfc(sqrt(xlookupCol1));
xlookup =transpose([index;xlookupCol2;xlookupCol1]);

Please let me know if you have any ideas/suggestions about how to rework the code to avoid this error. Thank you!