I hope somebody can help me. I'm trying to conduct an analysis which examines the number of samples of Hymenoptera caught over an elevational gradient. I want to examine the possibility of a uni-modal distribution in relation to elevation, as well as a linear distribution. Hence I am including `I(Altitude^2)`

as an explanatory variable in the analysis.

I am trying to run the following model which includes a Poisson error structure (as we are dealing with count data) and date and Trap Type (`Trap`

) as random effects.

```
model7 <- glmer(No.Specimens~Altitude+I(Altitude^2)+(1|Date)+(1|Trap),
family="poisson",data=Santa.Lucia,na.action=na.omit)
```

However I keep receiving the following error message:

```
Error: (maxstephalfit) PIRLS step-halvings failed to reduce deviance in pwrssUpdate
In addition: Warning messages:
1: Some predictor variables are on very different scales: consider rescaling
2: In pwrssUpdate(pp, resp, tolPwrss, GQmat, compDev, fac, verbose) :
Cholmod warning 'not positive definite' at file:../Cholesky/t_cholmod_rowfac.c, line 431
3: In pwrssUpdate(pp, resp, tolPwrss, GQmat, compDev, fac, verbose) :
Cholmod warning 'not positive definite' at file:../Cholesky/t_cholmod_rowfac.c, line 431
```

Clearly I am making some big mistakes. Can anybody help me figure out where I am going wrong?

Here is the structure of the dataframe:

```
str(Santa.Lucia)
'data.frame': 97 obs. of 6 variables:
$ Date : Factor w/ 8 levels "01-Sep-2014",..: 6 6 6 6 6 6 6 6 6 6 ...
$ Trap.No : Factor w/ 85 levels "N1","N10","N11",..: 23 48 51 14 17 20 24 27 30 33 ...
$ Altitude : int 1558 1635 1703 1771 1840 1929 1990 2047 2112 2193 ...
$ Trail : Factor w/ 3 levels "Cascadas","Limones",..: 1 1 1 1 1 3 3 3 3 3 ...
$ No.Specimens: int 1 0 2 2 3 4 5 0 1 1 ...
$ Trap : Factor w/ 2 levels "Net","Pan": 2 2 2 2 2 2 2 2 2 2 ...
```

And here is the complete data.set (these are only my preliminary analyses)

```
Date Trap.No Altitude Trail No.Specimens Trap
1 28-Aug-2014 W2 1558 Cascadas 1 Pan
2 28-Aug-2014 W5 1635 Cascadas 0 Pan
3 28-Aug-2014 W8 1703 Cascadas 2 Pan
4 28-Aug-2014 W11 1771 Cascadas 2 Pan
5 28-Aug-2014 W14 1840 Cascadas 3 Pan
6 28-Aug-2014 W17 1929 Tower 4 Pan
7 28-Aug-2014 W20 1990 Tower 5 Pan
8 28-Aug-2014 W23 2047 Tower 0 Pan
9 28-Aug-2014 W26 2112 Tower 1 Pan
10 28-Aug-2014 W29 2193 Tower 1 Pan
11 28-Aug-2014 W32 2255 Tower 0 Pan
12 30-Aug-2014 N1 1562 Cascadas 5 Net
13 30-Aug-2014 N2 1635 Cascadas 0 Net
14 30-Aug-2014 N3 1723 Cascadas 2 Net
15 30-Aug-2014 N4 1779 Cascadas 0 Net
16 30-Aug-2014 N5 1842 Cascadas 3 Net
17 30-Aug-2014 N6 1924 Tower 2 Net
18 30-Aug-2014 N7 1979 Tower 2 Net
19 30-Aug-2014 N8 2046 Tower 0 Net
20 30-Aug-2014 N9 2110 Tower 0 Net
21 30-Aug-2014 N10 2185 Tower 0 Net
22 30-Aug-2014 N11 2241 Tower 0 Net
23 31-Aug-2014 N1 1562 Cascadas 1 Net
24 31-Aug-2014 N2 1635 Cascadas 1 Net
25 31-Aug-2014 N3 1723 Cascadas 0 Net
26 31-Aug-2014 N4 1779 Cascadas 0 Net
27 31-Aug-2014 N5 1842 Cascadas 0 Net
28 31-Aug-2014 N6 1924 Tower 0 Net
29 31-Aug-2014 N7 1979 Tower 7 Net
30 31-Aug-2014 N8 2046 Tower 4 Net
31 31-Aug-2014 N9 2110 Tower 6 Net
32 31-Aug-2014 N10 2185 Tower 1 Net
33 31-Aug-2014 N11 2241 Tower 1 Net
34 01-Sep-2014 W1 1539 Cascadas 0 Pan
35 01-Sep-2014 W2 1558 Cascadas 0 Pan
36 01-Sep-2014 W3 1585 Cascadas 2 Pan
37 01-Sep-2014 W4 1604 Cascadas 0 Pan
38 01-Sep-2014 W5 1623 Cascadas 1 Pan
39 01-Sep-2014 W6 1666 Cascadas 4 Pan
40 01-Sep-2014 W7 1699 Cascadas 0 Pan
41 01-Sep-2014 W8 1703 Cascadas 0 Pan
42 01-Sep-2014 W9 1746 Cascadas 1 Pan
43 01-Sep-2014 W10 1762 Cascadas 0 Pan
44 01-Sep-2014 W11 1771 Cascadas 0 Pan
45 01-Sep-2014 W12 1796 Cascadas 1 Pan
46 01-Sep-2014 W13 1825 Cascadas 0 Pan
47 01-Sep-2014 W14 1840 Tower 4 Pan
48 01-Sep-2014 W15 1859 Tower 2 Pan
49 01-Sep-2014 W16 1889 Tower 2 Pan
50 01-Sep-2014 W17 1929 Tower 0 Pan
51 01-Sep-2014 W18 1956 Tower 0 Pan
52 01-Sep-2014 W19 1990 Tower 1 Pan
53 01-Sep-2014 W20 2002 Tower 3 Pan
54 01-Sep-2014 W21 2023 Tower 2 Pan
55 01-Sep-2014 W22 2047 Tower 0 Pan
56 01-Sep-2014 W23 2068 Tower 1 Pan
57 01-Sep-2014 W24 2084 Tower 0 Pan
58 01-Sep-2014 W25 2112 Tower 1 Pan
59 01-Sep-2014 W26 2136 Tower 0 Pan
60 01-Sep-2014 W27 2150 Tower 1 Pan
61 01-Sep-2014 W28 2193 Tower 1 Pan
62 01-Sep-2014 W29 2219 Tower 0 Pan
63 01-Sep-2014 W30 2227 Tower 1 Pan
64 01-Sep-2014 W31 2255 Tower 0 Pan
85 03/06/2015 WT47 1901 Tower 2 Pan
86 03/06/2015 WT48 1938 Tower 2 Pan
87 03/06/2015 WT49 1963 Tower 2 Pan
88 03/06/2015 WT50 1986 Tower 0 Pan
89 03/06/2015 WT51 2012 Tower 9 Pan
90 03/06/2015 WT52 2033 Tower 0 Pan
91 03/06/2015 WT53 2050 Tower 4 Pan
92 03/06/2015 WT54 2081 Tower 2 Pan
93 03/06/2015 WT55 2107 Tower 1 Pan
94 03/06/2015 WT56 2128 Tower 4 Pan
95 03/06/2015 WT57 2155 Tower 0 Pan
96 03/06/2015 WT58 2179 Tower 2 Pan
97 03/06/2015 WT59 2214 Tower 0 Pan
98 03/06/2015 WT60 2233 Tower 0 Pan
99 03/06/2015 WT61 2261 Tower 0 Pan
100 03/06/2015 WT62 2278 Tower 0 Pan
101 03/06/2015 WT63 2300 Tower 0 Pan
102 04/06/2015 WT31 1497 Cascadas 0 Pan
103 04/06/2015 WT32 1544 Cascadas 1 Pan
104 04/06/2015 WT33 1568 Cascadas 1 Pan
105 04/06/2015 WT34 1574 Cascadas 0 Pan
106 04/06/2015 WT35 1608 Cascadas 5 Pan
107 04/06/2015 WT36 1630 Cascadas 3 Pan
108 04/06/2015 WT37 1642 Cascadas 0 Pan
109 04/06/2015 WT38 1672 Cascadas 5 Pan
110 04/06/2015 WT39 1685 Cascadas 6 Pan
111 04/06/2015 WT40 1723 Cascadas 3 Pan
112 04/06/2015 WT41 1744 Cascadas 2 Pan
113 04/06/2015 WT42 1781 Cascadas 1 Pan
114 04/06/2015 WT43 1794 Cascadas 2 Pan
115 04/06/2015 WT44 1833 Cascadas 0 Pan
116 04/06/2015 WT45 1855 Cascadas 4 Pan
117 04/06/2015 WT46 1876 Cascadas 2 Pan
```