Validation failure

If the Formula is not properly formatted (for example, if the syntax is wrong, or it references a Tag which does not exist), the "Return Type" will display "Invalid," the "OK" button will remain unusable, and the "Validated:" text box will state the errors that exist.

If we change the example used before so that it references nonexistent Tags "SPressX" and "SPressY":

@ABS((@GETVALUE(SPressX,&NULL))-(@GETLASTVALUE(SPressY,&NULL)))>125

The validation will fail, and the "Validated" text will change to reflect the nature of the error:

If we change the original, correctly formatted formula so that it has one less "close parenthesis" than it needs, the "Validated" text will read "ERROR: Unmatched left parenthesis in expression" as follows:

After correcting the Formula as appropriate, the formula will Validate properly.