OFFSET vs MATCH in array formulas

Hi All,

I'm trying to streamline a worksheet by exchanging OFFSET for MATCH.

The sheet calculates a best fit curve by comparing various data after passing through three different models.

Two of the models work fine, but the third is failing.

I currently have this formula

{=MMULT(MINVERSE($J$15:$K$16),MMULT(TRANSPOSE(OFFSET($B$2,$K$1,0):OFFSET($B$2,$L$1,1)),OFFSET($E$2,$K$1,0):OFFSET($E$2,$L$1,0)))}

which I have replaced with this:

{=MMULT(MINVERSE($J$15:$K$16),MMULT(TRANSPOSE(INDEX(ln_Time,$K$1+1):INDEX(Unity,$L$1+1)),INDEX(Buoyancy_loss,$K$1+1):INDEX(Buoyancy_loss,$L$1+1)))}

where the named ranges are

Buoyancy_loss=Regression!$E$2:$E$1000
ln_Time=Regression!$B$2:$B$1000
sqrt_time=Regression!$D$2:$D$1000
unity=Regression!$C$2:$C$1000

However, I'm generating a #NUM error. Can anyone see where I've screwed it up?

Thanks