maximum amount of cells using CountA formula

I am trying to count the number of cells in a row that have data in them, it's actually "every other" column (i.e. i2, k2, m2, etc..) that I'm counting using the CountA formula, however, once I reach about 27 cells to count across, I get an error that says "more arguments have been specified for this function than are allowed in the current file format). I have 64 cells that need to be counted. So, my formula gets only so far (to BW2) and I get the error.

=COUNTA(I2,K2,M2,O2,Q2,S2,U2,W2,Y2,AA2,AC2,AE2,AG2,AI2,AK2,AM2,AO2,AQ2,AS2,AU2,AW2,AY2,BA2,BC2,BE2,BG2,BI2,BK2,BM2,BO2,BQ2,BS2,BS2,BU2,BW2)

I still have 30 more cells (every other cell) that I need counted. I'm sure this is easy but I can't find the answer. =(