Summary is not showing in the assembly if it is added as a reference

I've created a 'Class Library' in C#, which has many functions with summary (XML documentation comments).

For example

///<summary>
///Adds the two numbres
///</summary>
public void Add()
{
    //statements
}

if i use the function in the same namespace , its showing the summary, but if i added it as reference in some ohter workspace(solution) its not showing the summary.

How to make it visible i other solutions if a added it as a reference, and wat may be the reason for this?