formula in lotus approach (enter from another field, if current field

[maywat]

I am a newbie and need a bit help w formulas in lotus approach.

What I am trying to do is IF field A is blank to have the data from field B entered in field A,otherwise, to leave field A as is. Also, IF field B is blank (A is blank too), I want contents in field C to be entered in field A.

I tried something like the following but am not successful, obviously. I really appreciate any help anyone can give me. Thanks a million in advance.

If(IsBlank(field_A), (Fill(field_B),(otherwise leave this))

 

[PeVadeBo]

If(IsBlank(FieldA)="Ja";FieldB;FieldC)
You can also type a text or value in staid of a field.
Use 'text' to enter a text into this Field.

You can also use:
If( FieldA=''; FiledB; FieldC)

 

[PeVadeBo]

Correction!!!

don't use " but '
so 'Ja'
and two times ' for ''