Expression:Error: Calculated Column trying to convert to fraction instead of decimal

So i am trying to create a new calculated colum to calculate the true sales price of our products using a calculation, it seems simple enough except i am getting an Expression:Error and i cannot for the life of me work out why? The same calculation is working for half the date and there is no difference other then the numbers being used.

The error im getting is as follows: 

Expression:Error: We cannot apply operator / to types Text and Numbers.

Details

 Operator=/

 Left= 27.48

 Right=3

In my eyes this should be 9.16? Does anyone have any idea why this would be throwing an error? My calculations for the column are below: We have 4 wholesalers whos true sale price is calculated slightly differently. Wholesaler 4 is where im getting the error, but wholesaler 3 & 4 are excactly the same other then the wholesaler names?

net_sales_per_unit = 

if[Wholesaler Name] = "wholesaler1" then ([api_cost_price] -[claim_amount_per_unit])
else if[Wholesaler Name] = "wholesaler2" then ([net_sales_before_claim] / [quantity])
else if[Wholesaler Name] = "wholesaler3" then ([5iproducts.sell_price_1] - ([claim_amount] / [quantity]))
else if[Wholesaler Name] = "wholesaler4" then ([5iproducts.sell_price_1] - ([claim_amount] / [quantity]))
else 0