using embedded function with large matrices

I'm using a large matrix of size 18x18x18 in an embedded function but there is an error which says "EML requires variable to be fully difined". this error begins after i have assiged more than 200 elements of the matrix. and when i right click on the error there is an option to neglect it. may anybody please tell me what this error is and how i can solve it? i'm running matlab 2008a. thank you.

[Arnaud Miege]

Can you post the code you're using in your Embedded MATLAB Function block?