Remove line between FTB and slab

[justin.espejo701140]

Help! I can't seem to remove that line join between the FTB and slab. is there a way to cleanly join these elements or Am i forcing revit to do something wrong? Ive tried the join tool but to no avail. FTB-Slab Connection.png

[PijPiwo]

Join tool will do the job, but make sure both objects have exactly the same material.