Message Oracle LSX-00142 - invalid sub-element ~1S for element ~2S

ERRORinvalid sub-element ~1S for element ~2S
CAUSEThere was an invalid sub-element in the content of either the attribute or the element declaration. This was because the sub-element was either at the wrong position or out of context.
ACTIONRemove the sub-element or move it to the correct position.