parseLookup not returning correct value

I am currenlty trying do a calculated value that will do a lookup from a different sharepoint list based on a lookup field on the form.

I have tried three different formulas and I get two to render a respond but the prefix is not removed even when I have done the parseLookup formula. 

Formula one:  

lookup("Documents","Safety Standard Number and Title Description",parseLookup(SS Drop Down List),"POC")

Result:  1215#Valladares, Vanessa

Data Type:Sting

Formula two:  

String(lookup("Documents", "Safety Standard Number and Title Description", parseLookup( SS Drop Down List),"POC")).replace (/^null/gi,"")

Result:  1215#Valladares, Vanessa

Data Type:Sting

Formula three:  

parseLookup(lookup("Documents", "Safety Standard Number and Title Description", SS Drop Down List, "lookup:POC"))

Result:  (does not return a result)

Data Type:Sting

Can someone tell what I am doing wrong?  Your help is greatly appreciated.