Error 13: Type mismatch in VB

I am making a hotel reservation form with a dropdown menu for the room type and price of the room per night.
I keep getting this error in Visual Basic when I click the button to compute for the total price:
"Error 13: Type mismatch"
I tried to take the value of a textbox and a drop down menu.
I want to get the total when the user selects the room and multiply it with the number of nights they input in the textbox.
