Error at the Automask Step

Hi! I am getting the following error at the automask step and I am wondering how to proceed?

Reading images from "____" etc.

Fixed Clip level = 1507.574839

Used gradual clip level = 1325.819201 ... 1628.431869

Number voxel above clip level = 27351;

Clustering voxels...

??? Undefined function or method 'bwlabeln' for input arguments of type 'double'.

Error in ==> w_Automask>w_mask_clust at 306

[L , num]=bwlabeln(mask , RMM);

Error in ==> w_Automask at 58

mask = w_mask_clust(mask);

Error in ==> DPARSFA_run>(parfor body) at 1788

            w_Automask(InputDir, OutputFile);

Error in ==> parallel_function at 473

            F(base, limit);

Error in ==> DPARSFA_run at 1778

    parfor i=1:AutoDataProcessParameter.SubjectNum

Error in ==> DPARSFA>pushbuttonRun_Callback at 1779

    [Error]=DPARSFA_run(handles.Cfg);

Error in ==> gui_mainfcn at 96

        feval(varargin{:});

Error in ==> DPARSFA at 30

    gui_mainfcn(gui_State, varargin{:});

??? Error while evaluating uicontrol Callback

I have tried skipping the first few subjects at the automask step but receive the same error message each time I run the automask. I am using DPARSFA, SPM12, and Matlab  V.7.10.0 (64 bit).

I am also wondering whether automask is necessary for normalization with Dartel?