Convert string to range

Hi all!
I'm am very new to vba programming and have limited knowledge of excel, which is not a good combination.. =) Anyway, i'm trying to make a chart using a selection of cells. I loop the sheet and add each cell address i want (i'm looking for cells containing a specific word, then grabbing the address of the adjacent cell that contains a number). So i have a string (tmpFull) that looks like this, only longer. Each of these cells contain a number.

$B$12,$B$13,$B$14,$B$15,$B$16,$B$17,$B$18,$B$19,$B$21,$B$22,$B$27

I then need to assign this to my chart, so i "convert" the string to a range, or at least i'm trying to, using

Dim FullRng As Range
FullRng = tmpFull

And then add it to my chart (FullDatesRng made the same way)

With ActiveChart.SeriesCollection.NewSeries
    .Name = "Test"
    .Values = Worksheets("Raw Data").Range(FullRng)
    .XValues = Worksheets("Raw Data").Range(FullDatesRng)
End With

But no matter what i do, i end up with a 1004 error. I have tried building the string with different formats like B10,B11 or "B10,B11" and so on in different combinations but nothing works. Hoping for a pointer to what i'm doing wrong here.

Cheers!