Subset regression error?!


New Member
So I have 11 predictors and one response variable. I am wanting to look at the relationship (see what predictors effect the variable) and as I can't put all my predictors into multiple regression, I thought subsets would be best. Unfortunately when i enter all my data it comes up with the following message:

BReg '1' 'Acid grassland' 'Arable and horticulture' 'Bog' & 'Broadleaf woodland' 'Coniferous woodland' 'Heather' & 'Heather Grassland' 'Inland Rock' 'Suburban' 'Urban' ; NVars 1 10; Best 2; Constant.

ERROR * Total number of regression coefficients ≥ number of observations
I'm confused as I thought that subsets allowed for up to 31 predictors? (My data is all the same length)

Any help would be much appreciated