Sum from multiple selected field in form (1 Viewer)

Dear All,

Help!!! I have created a form. In the form there is a multiple selection field (called "Ind) from a table. You can select more then one field (as a multiple selection should...). This selection I would like to use to calculate the Sum of "omzet" from another table (tbl_OMZET) where the field "Code" is the same as the one(s) selected. Result should be displayed in field "Result" on the form. Can anyone help me and show me the right direction?

You will need to enumerate through the selected items and probably add those to a IN() clause in a query or DSum to then give you them total you want.
This thread shows a similar method for making a Where clause you should be able to adapt. https://access-programmers.co.uk/forums/showthread.php?t=231442