MI Impute Error

[Davia Downey]

Hi Statalisters,

I've encountered a problem with a MI impute code. The mIssing data table is below:

misstable patterns log_accessions pct_maori deprivationindex log_level6 pctbachelors pctmasters pctdoctorate turnover unemploymentrate15_oecd log_minority pct_allminorities log_eqcfunding log_ceraassistance

                    Missing-value patterns
                      (1 means complete)

              |   Pattern
    Percent   |  1  2  3  4    5  6  7  8    9 10 11 12   13
  ------------+----------------------------------------------
       <1%    |  1  1  1  1    1  1  1  1    1  1  1  1    1
              |
       61     |  1  1  1  0    0  0  0  0    0  0  0  0    0
       14     |  1  1  1  1    1  1  1  1    1  1  1  0    0
       11     |  1  0  0  0    0  0  0  0    0  0  0  0    0
        7     |  0  1  1  1    0  0  0  0    0  0  0  0    0
        2     |  1  1  1  0    0  0  0  0    0  0  0  1    1
        1     |  0  0  0  1    0  0  0  0    0  0  0  0    0
        1     |  1  0  0  1    0  0  0  0    0  0  0  0    0
        1     |  1  0  0  1    1  1  1  1    1  1  1  0    0
       <1     |  1  1  1  0    0  0  0  0    0  0  0  1    0
  ------------+----------------------------------------------
      100%    |

  Variables are  (1) unemploymentrate15_oecd  (2) log_accessions  (3) turnover  (4) deprivationindex  (5) log_level6  (6) log_minority  (7) pct_allminorities  (8) pct_maori  (9) pctbachelors
                 (10) pctdoctorate  (11) pctmasters  (12) log_ceraassistance  (13) log_eqcfunding

When I run the mi impute mvn code to fill in the missing values so I can run my analysis I get an error message.

 mi impute mvn log_accessions pct_maori deprivationindex log_level6 pctbachelors pctmasters pctdoctorate turnover unemploymentrate15_oecd log_minority pct_allminorities log_eqcfunding log_ceraassistance, burnin(1000) add(20) rseed (1234)

This is error messages: Performing EM optimization:
observed log likelihood = -295.64702 at iteration 100
(EM did not converge)

Performing MCMC data augmentation ...
Iteration 1601: variance-covariance matrix (Sigma) became not positive definite
posterior distribution is not proper
error occurred during imputation of log_accessions pct_maori deprivationindex log_level6 pctbachelors pctmasters pctdoctorate turnover unemploymentrate15_oecd log_minority pct_allminorities
log_eqcfunding log_ceraassistance on m = 8

I have no idea how to fix this. I've read the r(498) message but it isn't very informative. Any assistance would be greatly appreciated.