Hi Jose,

There are actualy three problems with the way you tried to call the function.

When calling matlab functions, you generally do not need the file extension. (This is what the error message is about.)

Also the BCT function expects the connectivity matrix itself and not the name of the file that contains it.
(I am guessing from the command you included that what you give the function as the argument is the name of the .mat file).

And there is also a more specific problem with this combination of the toolboxes that you use which will require an additional step.

So try the following:
1. Load the .mat file.
2. If I remember correctly, the connectivity matrices you get from ExploreDTI are stored in single variables named 'CM'.
3. In order for the BCT functions to work with ExploreDTI-s connectivity matrices, you need to zero out the values along the main diagonal (self connections)
4. Pass this processed CM to the BCT function.

In order to avoid mixing up the files, you can always read into a temporary variable (I'm guessing once again that you are going to use the functions on multiple subjects).

For example:
CM_Var = load( '06_DWI_FP_MD_C_trafo_Tracts_CSD_binary_PASS.mat' ); % This will be loaded as a struct, from which you can access the contents of the .mat file)
Connectivity_Matrix_Temp = CM_Var.CM;
Connectivity_Matrix_Temp = Connectivity_Matrix_Temp .* ~eye( size( Connectivity_Matrix_Temp ) );
Result = efficiency_bin( Connectivity_Matrix_Temp );

Hope this works.
Best wishes,
Gyula