I draw a rectngle and then the demensioning tool doesn’t work and the rectangle stays the same size
The dimensioning tool puts a dimension of a line or distance between two points on the model.
The tape measure tool shows the size of an object, places guidelines or scales the whole project.
Depending on the end result, what you want to use is either the push/pull, the scale or the move tools to change the size. (Or the entity info window)
What does it mean, “demensioning tool doesn’t work”?
What steps do you take and what do you expect the tool to do in subsequence?
The Dimension Tool only places a text display of the distance between the two points you choose. To change the size of something there are two ways that come to mind. The push/pull method will not grow a two dimensional object as someone else stated, but will allow you to grow it into a three dimensional object, adding thickness to the rectangle.
Use the Move tool. Select the line you want to move. Then hit ‘M’. you them grab the line and move it along the direction you choose. do this to two sides of a rectangle and you can ‘grow’ the rectangle.
Use the 'Scale" tool. this will place handles around the chosen object and allow you to manipulate it in various ways. be aware that this only works in percentages of growth or shrinkage. you cannot grow by fixed sizes.
Hope this helps.