Append characters to the trailing end of a field value even wehen the value is null

Hi All,

I'd appreciate any assistance with this question please.  I am using the following formula in a formula field to append percent signs (%) to the trailing end of the fields value:

numbervar requiredlength:= 60;

numbervar currentlength:= length({BR_CHG_Join_Mainframe_Code_Deployment.Categorization_Tier_3});

if requiredlength > currentlength then

{BR_CHG_Join_Mainframe_Code_Deployment.Categorization_Tier_3} + replicatestring("%", requiredlength-currentlength)

It works great when there is a value returned for the field but when the field returns a null value it leaves the field blank.  Any help or suggestions will be greatly appreciated.