[R] zero standard errors with geeglm in geepack

[miriza]

Hi!

I am using geeglm to fit a Poisson model to a timeseries of count data as
follows.  Since there are no clusters I use 73 values of 1 for the ids.  The
problem I have is that I am getting standard errors of zero for the
parameters.  What am I doing wrong?
Thanks, Michelle
>  N_Base
 [1]  95  85 104  88 102 104  91  88  85 115  96  83  91 107  96 116 118 103 
89  88 101 117  82  80  83 103 115 119  95  90  82  91 108 115  93  96  72
[38]  98  95  98  97 104  86 107  92  94  95 100 107  76 104 101  80 102 100 
91  96  89  71 109  97 113  99 127 115  91  81  73  69  92  90  78  57
> Year
 [1] 1932 1933 1934 1935 1936 1937 1938 1939 1940 1941 1942 1943 1944 1945
1946 1947 1948 1949 1950 1951 1952 1953 1954 1955 1956 1957 1958 1959 1960
1961
[31] 1962 1963 1964 1965 1966 1967 1968 1969 1970 1971 1972 1973 1974 1975
1976 1977 1978 1979 1980 1981 1982 1983 1984 1985 1986 1987 1988 1989 1990
1991
[61] 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2006

tes=geese(formula = N_Base ~ Year, id = rep(1, 73), family = "poisson",
corstr = "ar1")
> summary(tes)

Call:
geese(formula = N_Base ~ Year, id = rep(1, 73), family = "poisson", 
    corstr = "ar1")

Mean Model:
 Mean Link:                 log 
 Variance to Mean Relation: poisson 

 Coefficients:
            estimate san.se wald p
(Intercept)   7.1131      0  Inf 0
Year         -0.0013      0  Inf 0

Scale Model:
 Scale Link:                identity 

 Estimated Scale Parameters:
            estimate san.se wald p
(Intercept)     1.79      0  Inf 0

Correlation Model:
 Correlation Structure:     ar1 
 Correlation Link:          identity 

 Estimated Correlation Parameters:
      estimate san.se wald p
alpha    0.187      0  Inf 0

Returned Error Value:    0 
Number of clusters:   1   Maximum cluster size: 73 

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