If-else block follows AND block

In my project I use a, if-else block after a logical AND block. The AND port recieves two signal from input ports of dimension 8. It produces a signal of same dimension and redirect as incomming signal in the if-else block.

The error generated from the update diagram phase is:

_Error in port widths or dimensions. Output port 1 of 'model ' is a one dimensional vector with 8 elements.

Maybe it's due to how matlab manage the variable, it uses array or matrix. How can skip this problem ?