I've a list button which returns a URL & I need to add a condition based on the user id
IF(
$User.Id = Apttus_Proposal__Proposal__c.APTS_SalesDeveloper__c,
{!URLFOR('/apex/x?sObjectType=Apttus_Proposal__Proposal__c','sObjectId=' + Apttus_Proposal__Proposal__c.Id)},
"javascript:alert('You must be the Sales Developer for this Account to perform this action.');"
)
but when I try this formula, I'm getting this error -> Error: Enter a URL that is valid and well-formed.
Any suggestion about how to fix or configure the formula?