I am having a type mismatch error with this reference

Here is the code I am having an issue with. I am simply trying to input the value "0" into column G when the value in the corresponding row in column B is Deuterium. The debugger tells me my error lies with the line containing the If statement.

For i = 3 To 30
    If Worksheets("Master PEC").Cells(i, 2) = "Deuterium" Then
        Worksheets("Master PEC").Cells(i, 7).Value = 0
    End If
Next