Game Programming :: Function Always Returns False?

[VB.Net 2008 Express Edition]I have a 2D array of Integers called Map(0 to 79, 0 to 79)In this array I store IDs for tiles to be loaded later.I'm trying to write a module to generate a random dungeon every time it starts by making a room 10x10 tiles in the middle, picking a wall, making a hallway from that wall, and adding a room to the end of that hallway.From there it picks a random wall anywhere in the map, adds a hallway and a room, and repeats until the number of floor tiles is high enough [400 atm] The problem is that when the rooms and hallways are made, it first runs a function to return whether or not that space is empty. The problem is that even when I know for a fact the space is empty, it returns false. I don't understand why. Here's the Clear function.

Code:
Public Function Clear(ByVal Top As Integer, ByVal Left As Integer, ByVal Height As Integer, ByVal Width As Integer) As Boolean
'Returns whether a rectangle is empty
'used to loop through a rectangle of the map array
Dim introw As Integer

[code]....