clarify error message

matlab/dr1.m

@@ -363,6 +363,7 @@ else  % use original Dynare solver
     if info1
         info(1) = 2;
         info(2) = info1;
+        info(3) = size(e,2);
         return
     end
 

matlab/print_info.m

@@ -33,8 +33,9 @@ if ~noprint
         error(['The model doesn''t determine the current variables' ...
                ' uniquely'])
       case 2
-        error(['MJDGGES returns the following error code: ' ...
-               int2str(info(2))])
+        error(['The generalized Schur (QZ) decomposition failed. ' ...
+               'For more information, see the documentation for Lapack function dgges: info=' ...
+               int2str(info(2)) ', n=' int2str(info(3))])
       case 3
         error(['Blanchard Kahn conditions are not satisfied: no stable' ...
                ' equilibrium'])