Selecting A Variable Column Range

I have a workbook that generates sheets for each year based on selected criteria. It starts at Column H and goes too AH and beyond. When my loop reaches Z it errors out. I think this is happening because the code is referencing the column as ASCII. Here is the

Sub Test()
Dim d As Date
Dim yrint, i, num_years, fields, field_start As Integer
Dim yrstr, crit1, crit2, left_column_range_fixed, right_column_range_fixed, left_column_range_var, right_column_range_var, left_column_range, right_column_range, cost_column, cost_column_var, cost_column_fixed As String
left_column_range_fixed = "H"
right_column_range_fixed = ":AH"
cost_column_fixed = "2"
crit1 = "=x"
crit2 = ">0"
d = Date
yrint = Sheets("Overall"). Range("H2")
field_start = 9 'changed from 9....................