quick question for any one reading this

i have main mdi parant with a function on it , which needs to access the value of a textbox on a child form so i added the form to a module and when i code to acess the form i get all the parameters fine, but when i run the app i get an error message saying "object reference not set not set to an instance of the object"

i normally access forms in this way but ive never actully accessed a child from a parant but i cant see if being that difficult