a problem in using COM Builder

[lyrock]

Backgroud:

I just tried to compile a DLL file from COM Builder, in order to use it in a Visual Basic program.

the m file in Matlab is much simple, as follows:

function w=myBoxcar
w=boxcar;


Trouble:

when I call the function in Visual Basic, the following warning came out:

Function 'floor' not defined for variables of class 'int16'!


Question:
1. whether the trouble can be solved or not?
2. when I want to compile some other functions in Matlab for using in VB, I also met such a trouble, whether some operaters(or function) in Matlab can't be legal or translated in VB, how to solve this?

Thanks
Good Day!