Basically, we need to know what specific asset you are having this issue with.
First, understand that there are many situations where an asset classified as "residential rental real estate" will have a value of zero for the land. For example, if you put a new roof on the property, that's a property improvement that gets classified as rental real estate. Obviously, the value of the land for that specific asset will be zero.
Next, look at last year's form 4562. Understand that there are three of those form 4562's and you need to be looking at the right one. One prints in portrait format, the other two print in landscape format. You want the landscape format specifically titled "Depreciation and Amortization Report".
That form lists all your assets. Generally, the very first item on that list is the property itself, and it's the only one that has a value for the land. The only way any other assets would have a value for the land, is if you did actual qualified land improvements.
