Using Error.Type in a If statement

I am trying to set up a spreadsheet for our shipping manager. This spreadsheet has columns set up with Max, Min,Current Qty on hand, and a column for shippable qty. The column with the current qty. on hand is a V-LOOKUP formula (I don't want to change or loose this Look-up formula). The Max column (column C)has 20,
The Min column (column D) has 5, The current qty on hand column is the V-lookup which returned the error type #N/A or (7)this is column (E). The formula that I'm having the problem with is =IF(E7=D7,C7-E7,IF(E7>D7,0,IF(E7<D7,C7-E7,IF(ERROR.TYPE(E7)=7,C7,))))
What did I do wrong
Thanks
Charlie