Datalabel.Text randomly returns empty strings in a recursive function

I'm actually using VBA through Matlab... and I can't figure out if this is a Matlab or VBA problem so I'm posting on both threads. I'm using the following code:

Type_Linear = -4132;
Type_Poly   = 3;
% Type_Power  = 4;
% Type_Exp    = 5;

eC.SeriesCollection(1).Trendlines.Add(Type_Linear);
eC.SeriesCollection(1).Trendlines(1).DisplayRSquared = 1;
Lin_R_Squared = eC.SeriesCollection(1).Trendlines(1).DataLabel.Text
eC.SeriesCollection(1).Trendlines(1).DisplayRSquared = 0;
eC.SeriesCollection(1).Trendlines(1).DisplayEquation = 1;
Lin_y_Eq = eC.SeriesCollection(1).Trendlines(1).DataLabel.Text
eC.SeriesCollection(1).Trendlines(1).DisplayRSquared = 1;
% eC.SeriesCollection(1).Trendlines(1).DisplayEquation = 0;
Lin_R_squared_Cell = regexp(Lin_R_Squared,{'\d*[\.\d*]\d*[eE\d*][+-\d*]\d*','\d'},'match');
Lin_y_Eq_Cell = regexp(Lin_y_Eq,'[=\s][+-=\s][\s-]\d*[\.]\d*[eE+-\d*]+','match');

%Gets rid of the '=' in order to evaluate both positive and negtaive
%numbers to turn them into integers rather than strings
Temp = cell2mat(regexp(Lin_y_Eq_Cell{1},'[-\s]\d*\.\d*','match'));
Lin_y_Eq_Cell{1} = Temp;

eC.SeriesCollection(1).Trendlines.Add(Type_Poly,2);
eC.SeriesCollection(1).Trendlines(2).DisplayRSquared = 1;
Poly1_R_Squared = eC.SeriesCollection(1).Trendlines(2).DataLabel.text
eC.SeriesCollection(1).Trendlines(2).DisplayRSquared = 0;
eC.SeriesCollection(1).Trendlines(2).DisplayEquation = 1;
Poly1_y_Eq = eC.SeriesCollection(1).Trendlines(2).DataLabel.text
eC.SeriesCollection(1).Trendlines(2).DisplayEquation = 0;
Poly1_R_squared_Cell = regexp(Poly1_R_Squared,{'\d*[\.\d*]\d*[eE\d*][+-\d*]\d*','\d'},'match');
Poly1_y_Eq_Cell = regexp(Poly1_y_Eq,'[=\s][+-=\s][\s-]\d*[\.]\d*[eE+-\d*]+','match');
if cell2mat(Poly1_R_squared_Cell{2}) == '1'
    Poly1_R_squared_Num = str2num(cell2mat(Poly1_R_squared_Cell{2}));
else
    Poly1_R_squared_Num = str2num(cell2mat(Poly1_R_squared_Cell{1}));
end

Temp = cell2mat(regexp(Poly1_y_Eq_Cell{1},'[-\s]\d*\.\d*','match'));
Poly1_y_Eq_Cell{1} = Temp;

eC.SeriesCollection(1).Trendlines.Add(Type_Poly,3);
eC.SeriesCollection(1).Trendlines(3).DisplayRSquared = 1;
Poly2_R_Squared = eC.SeriesCollection(1).Trendlines(3).DataLabel.text
eC.SeriesCollection(1).Trendlines(3).DisplayRSquared = 0;
eC.SeriesCollection(1).Trendlines(3).DisplayEquation = 1;
Poly2_y_Eq = eC.SeriesCollection(1).Trendlines(3).DataLabel.text
eC.SeriesCollection(1).Trendlines(3).DisplayEquation = 0;
Poly2_R_squared_Cell = regexp(Poly2_R_Squared,{'\d*[\.\d*]\d*[eE\d*][+-\d*]\d*','\d'},'match');
Poly2_y_Eq_Cell = regexp(Poly2_y_Eq,'[=\s][+-=\s][\s-]\d*[\.]\d*[eE+-\d*]+','match');
if cell2mat(Poly2_R_squared_Cell{2}) == '1'
    Poly2_R_squared_Num = str2num(cell2mat(Poly2_R_squared_Cell{2}));
else
    Poly2_R_squared_Num = str2num(cell2mat(Poly2_R_squared_Cell{1}));
end

Temp = cell2mat(regexp(Poly2_y_Eq_Cell{1},'[-\s]\d*\.\d*','match'));
Poly2_y_Eq_Cell{1} = Temp;

This code is supposed to add three trendlines to a graph and pull out the string value for each trendline using datalabel.text. This code is actually in a function and run recursively in my main script, however, sometimes when I change certain variables, datalabel.text will return an empty string and I can't figure out why.

Please let me know if you know why this is doing this!! Thanks.