Help, sum 2 field values to 3rd field

[Craftsman55]

Please help! I have been trying to build an expression in Access Professional 2013 with no luck. I have an Asset Maintenance Sub-form added to my Asset Form. On the Maintenance Sub-form I have 3 fields: Service cost, parts cost and Total cost. I would like to do is when I enter an amount in Service cost &/or Parts cost have it automatically insert the total into Total cost. I have entered this expression: [Total cost] = ([Service cost] + [Parts cost]) in various forms and nothing works.

[Missinglinq]

Entered it where..in what event?

First, you have to understand that Anything + Null (an empty Textbox) = Null. To have Service Cost or Parts Cost entered in the Total Cost Textbox, you need to allow for one of them being empty...so, in VBA in an event (in the AfterUpdate event of the Service cost and Parts cost Controls, you'd use

[Total cost] = (Nz([Service cost],0)) + (Nz([Parts cost], 0))

which converts a Null value to Zero.

Or, in the Control Source Property (in Properties - Data) for [Total cost] you'd use

= (Nz([Service cost],0)) + (Nz([Parts cost], 0))

The latter suggestion is probably the one you should be using.

Linq ;0)>