I guess, VFP gets confused in this case because '.' dot can be used between object and it's property and table and it's field. Try to assign the property value to the memory variable and use that variable in the SEEK.

case !empty(Thisform.txtpg_no.value)
 WITH ThisForm.txtPG_NO
    m.SeekValue = .value
    do case
          
    case !seek(m.SeekValue,"pgappl","ONLYPGNO")
    endcase

>I am running this line of code
>

>case !empty(Thisform.txtpg_no.value)
> WITH ThisForm.txtPG_NO
>    do case
>      case !seek(.value,"pgappl","ONLYPGNO")
>    endcase

>and i am getting this error: "Object is not contained in a FORMSET"
>I have no clue what this is referring to since I am not referencing a formset at all.
>Does anyone have any help on this????
>Thanks.
>Shevy