Errors with mergePatchPairs
 

Pleas I am really confused on how to merge two faces for an internal geometry. I have tried the instructions in the docs but I still keep getting errors and the errors are not descriptive enough for me to decipher. I have been battling with creating an internal baffle in my geometry for weeks now. My blockMeshDict is shown below along with the attachment of my case Attachment 33933

Thanks for any help

vertices
(
(0 0 0) //0
(1 0 0) //1
(1 1 0) //2
(0 1 0) //3
(0 0 0.1) //4
(1 0 0.1) //5
(1 1 0.1) //6
(0 1 0.1) //7


(0.2 0.5 0) //8
(0.8 0.5 0) //9
(0.8 0.6 0) //10
(0.2 0.6 0) //11
(0.2 0.5 0.1) //12
(0.8 0.5 0.1) //13
(0.8 0.6 0.1) //14
(0.2 0.6 0.1) //15

);

blocks
(
hex (0 1 2 3 4 5 6 7) (20 20 1) simpleGrading (1 1 1)
hex (8 9 10 11 12 13 14 15) (20 2 1) simpleGrading (1 1 1)
);

edges
(
);

boundary
(
ceiling
{
type wall;
faces
(
(3 7 6 2)
);
}
floor
{
type wall;
faces
(
(1 5 4 0)
);
}
fixedWalls
{
type wall;
faces
(
//(0 4 7 3)
(2 6 5 1)

(8 9 13 12)
(11 15 14 10)

//(8 12 15 11)
(9 10 14 13)
);
}
frontAndBack
{
type empty;
faces
(
(0 3 2 1)
(4 5 6 7)

(12 13 14 15)
(8 11 10 9)
);
}
obstructionSide
{
type wall;
faces
(
(8 12 15 11)
//(9 10 14 13)
);
}
sideWall
{
type wall;
faces
(
(0 4 7 3)
);
}
);

mergePatchPairs
(
(sideWall obstructionSide)
);

// ************************************************** *********************** //