Salesforce Triggers cannot calculate a "Null" (Blank) Value. Fields on the Sale and Sale Items must be populated with at least a '0' (zero). If any fields are Blank, you will see a Null Pointer Exception error (see screen shot below).
In improveit 360's Products and Materials Package, and Supportworks Package, users can Assign Sale Items and their related Materials to a Project. This gives your Foremen and Warehouse Managers an itemized list of the inventory needed for each Installation. This Article covers common troubleshooting issues to check, if your Sale Items or Materials are not relating to a Project when you've used the "Assign Sale Items" button.
Overview: When on a Sale or Project and assigning sale items to projects the Sale Item Trigger Utilities will calculate the Project Price by multiplying the Quantity and Unit Price of the sale items by the Tax Rate and then stamping that dollar amount in the Project Price field for the sale items related to that project. If the Sale item does not have a Quantity or Unit Price or the sale as a whole doesn't have a Tax Rate the automation sees a "Null" (Blank) Value and will rollback, thus not creating the relationship of the Sale Items to the Projects in which you are assigning.
Consideration: If one of the Sale Items has a "Null" (Blank) Quantity or a "Null" (Blank) Unit Price, OR the Sales Tax Rate is "Null" (Blank) the assignment of all Sale Items will rollback and Sale Items will not be assigned. In some cases, this will also prevent a Sale from Saving. See examples below:
Example A: Sale Item Quantity is Null (Blank)
Resolution: Insert a 0 Quantity and/or a $0 Unit Price and then Assign the Sale Items. As long as the Value for Quantity and Unit Price are not Blank (Null) the Sale Items will be related to the Project.
Example B: Sales Tax Rate is Null (Blank)
Reason: Salesforce Triggers cannot calculate a "Null" (Blank) Value, these Fields must be populated with at least a '0' (zero).