Calling multiple function in Add In (.NET)

[Anbu]

Hi,

I have an Add In created in .NET for MS Project 2003. This addin has 3
modules and have corresponding Menu Items in MS Project. When
I access any of the function in the add In for the first time, it works
fine. But the same could not be executed using the same menu
item. But there is one more menu item (belonging to the same Add In) works
fine even other items are not working well.

Can anyone suggest me what's wrong with the Add In application?

TIA.