Try this to add a niche

	In plan view, draw a polyline inside the wall to represent the niche.
	Go to the Design menu, select Wall Tools, then select Convert Polyline to Wall Modifier.
	At the Select a wall: prompt, select the wall that will have the niche.
	At the Select a polyline: prompt, select the polyline that represents the niche.
	At the Erase layout geometry? [Yes/No] <N>: prompt, type "Y" (for Yes) and press Enter.
	In the New Wall Modifier Wall Name dialog box, type a name to represent the niche. The name should be descriptive so it is obvious when there are multiple wall modifiers.
	Pick the OK button to exit the dialog box.
	At the Add Wall Modifier dialog box, go to the Component Name option and select the wall component from the drop-down list to which you are attaching the wall modifier (niche). (The component name(s) listed will depend on the wall style to which the wall modifier is attached.)
	In the Start Elevation Offset and End Elevation Offset options, enter the distance of the bottom and top of the niche from the desired location as selected from the drop-down lists at the right of the dialog box. *Note:* To get the top of the niche to come "down" from the top, enter a negative value for the offset distance. A positive number makes the niche go "above" the wall.
	Pick the OK button to exit the dialog box.

Note: See Changing an existing wall modifier on method to change the niche after it is placed.

Change an existing wall modifier:

	Highlight the wall that contains the wall modifier.
	Right-click and select Wall Properties from the popup menu.
	In the Wall Properties dialog box, go to the Wall Modifiers tab.
	In the large box at the top of the dialog box, highlight the desired wall modifier name in the Style column.
	Parameters for the selected wall modifier are displayed in the lower portion of the dialog box. Modify the desired parameters.
	Pick the OK button to exit the dialog box.