Change the margin of a specific cell's table

[leprofca]

I have a table that has just a row and 7 columns. The third column was middle justified and I changed that to middle left. But now the texte is too close to the left. I would like to change the margin of that cell only.

I tried: (vla-put-HorzCellMargin (vlax-ename->vla-object (entlast)) 2.0) but that change the margin of all cells and that screw up my table. Then I tried (vla-setmargin (vlax-ename->vla-object (entlast)) 1 3 0.06 2.0) but I get an error saying: Automation Error. Currently write protected.