Problem updating to newer version of lme4

I just updated to the new lme4 (v28), but now it will not load the 
library and I get the following message:

Error in inDL(x, as.logical(local), as.logical(now), ...) :
  function 'cholmod_l_start' not provided by package 'Matrix'
In addition: Warning message:
package 'lme4' was built under R version 2.7.2
Error: package/namespace load failed for 'lme4'

Benjamin Zuckerberg, Ph.D.
Post-doctoral Associate
Spatial Ecologist, Citizen Science
Cornell Laboratory of Ornithology
159 Sapsucker Woods Road
Ithaca, NY 14850 
Tele: 607-254-2174
Fax: 607-254-2111