error - unexpected matlab expression

I have the following call to a function:

    callfun(I1, I2, [X Y ones(n,1)], w, m)

But, I'm getting:

    Error: File: callfun.m Line: 20 Column: 3
    Unexpected MATLAB expression.

Why is that?

Thanks.

[Star Strider]

Post the complete code to the callfun function.

[dpb]

Even better would be the full error message in context -- the error is inside the function callfun, not the call to it...there's a syntax error there but we're not given that line.